The terminology of identities between, outside and beyond the gender binary – A systematic review

Abstract

Background: Recently, a multitude of terms have emerged, especially within North America and Western Europe, which describe identities that are not experienced within the culturally accepted binary structure of gender which prevails within those cultures. As yet, there is no clear single umbrella term to describe such identities and a mixture of words have been used in scholarly work to date.

Aims: To explore the origins and track the emergence of newer terms and definitions for identities between, outside and beyond the gender binary, to outline current trends in descriptors within scholarly work and to suggest a term which is wide enough to encompass all identities.

Methods: A comprehensive systematic review was made, following the PRISMA guidelines. Several relevant key terms were used to search Web of Science, ScienceDirect, PubMed, and the International Journal of Transgenderism. The descriptions each title gives for identities outside of the binary are extracted for analysis.

Results: Several terms have been used over the years to describe identities outside of the binary. “Non-binary” and “genderqueer” are currently mostly used as umbrella terms. However, “gender diverse” is emerging as a more suitable wide-ranging inclusive term for non-male and non-female identities.

Discussion: Identity outside of “male” and “female” is an emerging concept which currently has several identifiers and little academic agreement on which is the most pertinent. The two leading descriptors are “non-binary” and “genderqueer.” Gender diverse is emerging as a new term which has the aim of including all other terms outside of male and female within it and this article suggests the increase in its use to describe gender identities outside of the binary.

Introduction

In recent years, various descriptors have emerged which define identities that fall somewhere between, outside or beyond the gender binary (Richards, Bouman, & Barker, 2017). Individuals who do not identify with the gender binary may have been assigned either “male” or “female” at birth and will generally have at one time possessed a body that corresponds with “male” or “female” sex. However, bodies of individuals who identify outside of the binary vary greatly with many people undergoing gender affirmation treatments and other bodies being intersex from birth (Richards et al., 2016). What binds people who identify this way is that they all share a sense that at their core, they do not identify as “male” or “female” (Kuper, Nussbaum, & Mustanski, 2012).

The concept of gender identities as part of the transgender narrative outside of the binary within research is a recent concept. Literature explicitly exploring this gender expression only stretches back to the first decade of this millennium (Factor & Rothblum, 2008; Haritaworn, 2008). Yet the concept of a “third gender” or an identity that cannot be placed within the generally accepted “male” or “female” identifiers is not new. From the earliest records, figures such as the Greek God Hermaphroditus (Grimal, Kershaw, & Maxwell-Hyslop, 1990) and the Sumerian Gala Priests of ancient Mesopotamian cities (Suter, 2008) have represented individuals who are not easily identified as “male” or “female.” Philosophers and some early Christian leaders actively promoted androgyny as the original and ideal state for a human (Cobb, 1993). In pre-Columbus America, there are historical reports of many tribes holding the belief that there were, in fact, four genders – “male,” “masculine,” “feminine,” and “female,” although these categories are of course viewed through a very Western concept of gender identity and the exact practicality of these identities cannot be condensed into four categories so easily. Diverse gender identities were discouraged by Christian immigrants, as were the traditional “Two-Spirit” identities in many tribes, who were sometimes re-named by the immigrants with disparaging terms and generally discriminated against (Estrada, 2011). The advent of Christianity saw many cultures adhere to strict binary “male” and “female” roles imposed upon them by the religion. However, fashion has often had periods when androgyny is en vogue, such as the 1920s, 1960s, and the current day (Townson, 2016).

Within academic literature, identities that are not binary are now discussed as a trans identity and many of those who exhibit such gender expressions often also consider themselves to be trans (Richards et al., 2017). The unique experience of those identifying outside of the binary is only just starting to become the subject of in-depth research. More than half the total number of publications ever printed on transgender issues have been published since 2010 (Matsuno & Budge, 2017), yet a relatively low number focus on (or even include) gender identities that are not binary. With the number of people identifying outside the binary increasing rapidly, there is an urgent need to expand research in this area (Practical Androgyny, 2018).

The terms used to describe identities that do not conform to the gender binary change at a fast pace and there are multiple descriptors in constant use among this population, each nuanced towards a precise and often very personal gender identity, experience and expression (Matsuno & Budge, 2017). How an individual arrives at a gender identity that is not “male” or “female” is currently lacking in research. Stachowiak (2017) describes how being outside of “male” and “female” is not clearly defined but as “organic and personal” (p. 532) which includes many negotiations of social and lived experiences of gender. This very personalized journey has not only led to a flurry of different identifiers (e.g., Kuper et al., 2012), but also there is a notable lack of cohesive single description in scholarly work for identities that do not fit within the binary.

The overarching aim of this review is to critically review the ways in which identities that are not “male” or “female” have been described within scholarly research and how that definition has evolved through the last five decades. In order to understand research into these identities, it is essential to know and understand the terms that have been employed throughout the history of research on the subject. Early studies questioning the concept of a binary gender system and studies examining historical gender variants in other cultures are a good starting point to explore how this gender expression evolved. This article looks at the terms that have been used to identify people outside of the binary and places them within their historical context before moving on to suggest a suitable defining term and future research on this subject.

Methods

Searching strategy

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (Moher, Liberati, Tetzlaff, Altman, & The PRISMA Group, 2009) guidelines were followed to undertake this systematic review. For this review, keywords were generated by a scoping review of core papers and books as well as discussions with other researchers in this area. Search terms were also added as new terms emerged during the progress of the review. Initially, the search terms used within this study were: “non-binary” gender, genderqueer, genderfluid, androgyne, bigender, “two-spirit,” and “third gender.” Quotations marks were used on some of the keywords to further refine the search (e.g., the word “non-binary” left the results saturated with computer science papers). Within the results of the search, some of the material contained descriptors that had not been added into the initial search (PoMoSexual, Psychological Androgyny, Hijra, Genderfuck, Gender diverse). The search was extended using these key terms in order to ensure that literature using these descriptors was not overlooked. Relevant filters on each database were applied. All articles found had full-text access within the libraries in which they were found. Books that were not available online were sought via the University of Nottingham library service (two books that were not available online were sourced this way). The search engines used were: Web of Science, ScienceDirect, and PubMed. These databases were chosen as they contain a wide selection of publications. A search following identical inclusion criteria was also carried out within the archives of the International Journal of Transgenderism, which is considered the main publication in this area of research. A separate search of this journal was included as at the time of the search it was not indexed on the search facilities used and it was considered to contain papers vital for a comprehensive view of this subject. Both articles and books were found using these search engines. Reference lists of the articles and books found were also searched for relevant material. The research took place between May 22, 2018 until September 7, 2018.

Inclusion and exclusion

The review only considered peer-reviewed articles either reporting original research or presenting theoretical stances and ideas. This reflected the aims of the review but also encompassed the two areas of study most likely to contain scholarly work on gender. Publications between January 1, 1960 and August 2018 were included in the search. The 60s were considered a good starting point as this coincides with a time when the women’s liberation movement began to actively interrogate the assumed roles of “male” and “female” within society and question the biological determinism that was widely accepted as a key difference between “males” and “females.” Only publications in English were included.

As the aim of the review is to examine the main terms used to describe identities that are not male or female and to examine the description of these overarching terms, it was imperative all literature selected contained a description of the key term used and that the studies focused primarily on those who do not identify as “male” or “female.” Therefore, only publications where descriptions of terms used for people between, outside or beyond the gender binary available were included. Review and meta-analysis papers were excluded as this review aims to focus on original research and also to ensure that descriptors analyzed were not duplicated within other reviews.

Screening

Papers were first selected by their title and those that did not meet the inclusion and exclusion criteria (see Table 1) were removed from the search. The abstracts were then read and those which did not meet the criteria at this stage were removed. The remaining papers were then studied in full, with noteworthy information being extracted from the publications while those papers that were not relevant were excluded. Where papers included key terms but did not give a detailed description, these papers were removed at the reading stage. Key books were also identified within the initial search or added after the reading stage, having been referenced in one of the papers or books already included within the initial search. The results of the search were compared with an identical search carried out by a second researcher (EM). Both searches produced similar results. Any discrepancies were reviewed and agreed between both researchers (NT and EM).

Table 1.

Inclusion and exclusion criteria.

Inclusion	Exclusion
Published (in print or online) from 1960 until October 2018	Not written in English
Written in English	No description of identifier
Body test contains keyword plus a description of identifiers describing an identity that is neither male nor female	Reviews or meta-analysis
Peer-reviewed publications, books, and chapters	Comment or editorial pieces

In total, 435 texts were identified for inclusion by their titles from the initial search. This number was reduced to 239 after the duplicates were removed. A total of 46 texts were removed at the title reading stage and 107 papers were excluded at the abstract reading stage as they did not meet the criteria. The remaining 82 texts were downloaded for review with 47 being excluded for not meeting the criteria (45 contained no detailed description of the terms used, two were editorial articles). A total of four books were also found under the search criteria and three through references in material already found in papers via the search criteria. Therefore, a total of 39 titles were included in this review – 31 papers, six books, and two book chapters. Where only a chapter was found to be relevant, this chapter is specifically noted. If the whole book was of relevance, then the book is cited, but not specific chapters (Figure 1).

Figure 1.

Process of identifying relevant literature.

Overview of literature

There were a mixture of quantitative experiments, qualitative studies, and theoretical articles as well as one neurological study (Case & Ramachandran, 2012). Most of the early articles focused on individual differences, especially in relation to masculine and feminine traits (Bem, 1974; Berzins, Welling, & Wetter, 1978; Gilbert, 1981; Wiggins & Holzmuller, 1978). Three articles were investigating gender identities outside of “male” and “female” in nations other than non-Western cultures, namely “Two-Spirit” in Native American society and the “third gender” or “Hijra” in India (Goulet, 1996; Taparia, 2011; Wilson, 1996). Three of the qualitative articles focused on the lived experience of identifying outside of the binary (Corwin, 2017; Darwin, 2017; Stachowiak, 2017) and one looked at dysphoria in “bigender” identifying people who live alternately as either “male” or “female” depending on how they feel at any given time (Blechner, 2015). There were also three articles commenting on a paradigm shift, two from the 1980s describing a shift away from “masculine” and “feminine” traits being seen as unidimensional model (Bockting, 2008; Diamond & Butterworth, 2008; Robinson & Green, 1981) and a later article examining the shift away from strict binary sex role categories within transgender healthcare settings (Koehler, Eyssel, & Nieder, 2018). In terms of books, the oldest was published in 1997 (Queen & Schimel, 1997)and the latest was published in 2017 (Richards et al., 2017). Several key terms emerged from the literature and are presented here in chronological order.

Results

Various terms were found during this review, which were detailed in Tables 2 and 3. From these terms, several key identifiers and umbrella terms were found which occurred in several articles, papers and/or provide interesting data on the emergence of terms which relate to the aims of this study. These key terms are detailed below (Table 4).

Table 2.

Characteristics of peer-reviewed papers.

Year	Author	Country	Design	Search term	Definition
1974	Bem (1974)	UK	Quantitative	Psychological Androgyny	Individuals may have both “masculine” and “feminine” traits
1978	Wiggins & Holzmuller (1978)	USA	Quantitative	Psychological Androgyny	Those who have both positive and negative traits normally related to either gender roles
1978	Berzins et al. (1978)	USA	Quantitative	Psychological Androgyny	“Appropriately” masculine men and feminine
1981	Gilbert (1981)	USA	Theoretical	Psychological Androgyny	Androgynous persons combine the traits and behaviors of both men and women
1981	Robinson & Green (1981)	USA	Theoretical	Psychological Androgyny	An alternate sex-role model. A dynamic and flexible orientation of life in which assigned gender is irrelevant
1996	Wilson (1996)	USA	Theoretical	Two-spirit	Two-spirit people were thought to be born in balance with both male and female characteristics
1996	Goulet (1996)	USA	Theoretical	Berdache	A distinct third gender which incorporates both male and female characteristics
2000	Ward (2000)	NZ	Quantitative	Psychological Androgyny	Comparable levels of male and female traits
2005	Fitzpatrick et al. (2005)	USA	Quantitative	Psychological Androgyny	Androgyny is defined as high levels of masculine and feminine traits Cross-gender refers to a “mis-match” between actual gender and gender role
2008	Bockting (2008)	USA	Theoretical	Genderqueer	A number of transgender people transcend the dichotomous view of gender
2008	Diamond & Butterworth (2008)	USA	Case study	Psychological Androgyny	Continued movement between, around, and within gender polarities
2010	Kaufmann (2010)	USA	Case Study	Psychological Androgyny	Both male and female, either male or female or neither male nor female. A multiplicity of genders and sexes
2011	Taparia (2011)	India	Theoretical	Hajra	Individuals possessing both male and female sexual characteristics
2012	Case & Ramachandran (2012)	USA	Neuroscience	Bigender	People who switch between fixed male and female identities sometimes hourly or sometimes yearly and sometimes when the switch is not welcomed
2014	Budge et al. (2014)	USA	Quantitative	Genderqueer	Individuals who do not identify as entirely male or female and may feel that their gender identity is somewhere on a spectrum
2015	Blechner (2015)	USA	Psychoanalysis	Bigender	People who combine male and female gender identities
2017	Corwin (2017)	USA	Qualitative	Genderqueer	Self-defined as one’s identity falling outside of the male/female gender binary
2017	Darwin (2017)	USA	Qualitative	Non-binary	Some identify as part of a five par model (masculine, masculine of center, androgynous, feminine of center, feminine) while others consider themselves as a “no gender” category between male and female. Others consider themselves both male and female
2017	Factor & Rothblum (2017)	USA	Quantitative	Genderqueer	Experience gender as shifting over time, feel it is continuous, dress in a “gender blending” way and believe there are more categories than male and female
2017	Stachowiak (2017)	USA	Qualitative	Genderqueer	A “contested terrain,” simultaneously stereotyped and dismissed, a felt sense and a socially constructed sense of gender
2018	O’Shea (2018)	UK	Qualitative	Non-binary	A gender identity viewed as “not normal” by the predominant heterosexual matrix
2018	Broussard et al. (2018)	USA	Quantitative	Gender non-binary	Those whose gender identity do not conform to female/male dichotomy
2018	Monro & Van der Ros (2018)	UK Norway	Qualitative	Non-binary	“People [who] have a gender which is neither male nor female and may identify as both male and female at one time, as different genders at different times, as no gender at all, or dispute the very idea of only two genders” (cited from Richards et al., 2016)
2018	Koehler et al. (2018)	Germany	Quantitative	Non-binary and genderqueer (NBGQ)	Individuals identify with a gender that is temporarily or permanently neither exclusively masculine and feminine parts, oscillates between genders, is situated beyond the binary, or rejects the binary
2018	Esmonde et al. (2018)	USA	Qualitative	Non-binary	Experience their identity as separate from – or over-lapping with – the gender binary of male or female
2018	Taylor et al. (2018)	UK	Qualitative	Non-binary	People who do not identify with the male/female binary, but still struggle with gender dysphoria
2018	Fiani & Han (2018)	USA	Qualitative	Non-binary	Part of a “second wave” trans identity which tappers away from the extremes of male and female
2018	Clark et al. (2018)	Canada	Quantitative	Non-binary	Gender does not always align with sex assigned at birth. Gender may fluctuate between genders or be fixed
2018	McGuire et al. (2018)	USA Netherlands	Quantitative	Genderqueer	Identify as both, or between, masculine and feminine
2018	Bradford et al. (2018)	USA	Qualitative	Genderqueer	Neither opt to assimilate with a binary identity nor oppose it
2018	Lykens et al. (2018)	USA	Qualitative	Genderqueer Non-binary	People who live outside the gender binary and describe their identity as both man and woman, either, or no identifiable gender

Table 3.

Characteristics of books and chapters.

Year	Author	Country	Term (s) used	Definition
1997	Queen & Schimel (1997)	USA	PoMosexual	Not intended as a widely-adopted label or a new identity. Describes people who have no fixed sexuality and/or gender. The term is a backlash and criticism of fixed gender and sexuality terms the LGBT + community has adopted
1997	Wilchins & Serano (1997)	USA	Genderqueer	The term transgender has extended to include any type of “genderqueers” who don’t change their genitals
2002	Nestle et al. (2002)	USA	Genderqueer	People who express their gender in ways that defy cultural norms. They don’t follow the rules or grammar of gender
2008	Girshick (2008)	USA	Genderqueer	Those who find the gender binary “inhibiting” and feel their identity is outside of it
2015	Richards & Barker (2015)	UK	Non-Binary	Umbrella term for those who have no gender, incorporate aspects of both genders, are to some extent but not completely one gender, are an additional gender, move between male and female or disrupt the binary
2017	Richards (2017)	UK	Non-Binary	People who do not identify as male or female. May have a fixed or fluid identity or eschews the notion of a gender spectrum altogether
2017	Richards et al. (2017)	UK	Genderqueer and Non-Binary	People who are not male or female. Refers to identity rather than physicality. Does not exclude intersex
2018	Hines & Taylor (2018)	UK	Gender fluid Genderflux Non-Binary Gender Diverse Genderqueer	Genderfluid – people experience their gender as changing over time. Non-binary – describes a gender category outside of male and female. Genderflux – people experience their gender identity or expression as more or less intense at different times. Non-Binary – describes any gender identity or expression outside the categories of male and female. Gender diverse – a gender diverse person does not conform to their society’s norms or values when it comes to their gendered physicality, gendered identity, gender expression or combination of those factors. Genderqueer – like non-binary, describes someone whose gender identity does not sit within the social norms of masculine or feminine, but between or outside these binaries

Table 4.

Summary of findings.

Term	Date of first appearance within this review	Summary of definition
Psychological Androgyny	1974 (Bem, 1974)	Individuals who show signs of traits that are considered to be “masculine” as well as traits that are considered to be “feminine”
Two-Spirit (Berdache)	1996 (Wilson, 1996)	A traditional Indigenous American term for those who embody “male” and “female” spirit. Berdache is considered to be an outdated and derogatory term created by European settlers to deride two-spirit peoples
PoMoSexual	1997 (Queen & Schimel, 1997)	A term not designed to be used widely which describes the movement away from sexuality and gender as fixed and rigid categories
Genderqueer (also spelled “gender queer”)	1997 (Wilchins & Serano, 1997)	Those who feel their gender is neither “male” nor “female.” Some papers and books imply genderqueer is often used by those who object to “male” and “female” as a cultural norm and so the term has a political element to it
Non-binary (also spelled “nonbinary”)	2015 (Richards & Barker, 2015)	An umbrella term for those who feel their gender identity is between or outside of “male” and “female”
Gender Diverse	2018 (Hines & Taylor, 2018)	A person who does not conform totally to society’s norms for their assigned gender at birth

“Two-Spirit” and “Hijras”

The majority of the papers in this review were produced in the USA or the UK and so there is naturally a very Western bias to the material produced. Several studies, however, did examine two notable groups in societies within non-Western cultures – “Two-Spirit” and “Hijras.” Wilson (1996) describes a few of the misunderstandings of the term “Two-Spirit,” which relates to a historical concept within Indigenous American people. In her study, she describes how the term is often erroneously used as an umbrella term for the whole of the LGBT community when in fact, “Two-Spirit” traditionally refers to a distinct gender presentation which is neither “male” nor “female.” Goulet (1996) comments on how the term is further misunderstood due to the European settler’s interpretation of “Two-Spirit” people as deviant and giving them the label “Berdache,” a derogatory term for a homosexual with strong feminine tendencies. Goulet’s article also highlights the problem of no unified definition of “Two-Spirit.” Indigenous North American culture is based upon a tribal system. Whilst some tribes held “Two-spirit” people in high esteem, in others, they simply assimilated into everyday life while in other tribes, “Two-spirit” people were not recognized at all. Similar issues were described by Taparia (2011) in relation to the recognized third-gender culture in East Asia, known as the “Hijra.” Like “Two-Spirit” people, the term has been subject to historical confusion and at various times been used to describe other groups in society such as homosexuals and eunuch people.

The role of the “Hijra” is also an ever-changing one which ceremonial importance being noted in history, but roles such as tax collection and sex work being strongly related to the “Hijra” today (Subramanian et al., 2015; Taparia, 2011). Taparia (2011) described how the identity of the Hijra has been imposed, restricted, and negotiated through history with the basic concept of an emasculated “male” body remaining the core of the identity (Taparia, 2011). The Hijra is widely considered as being neither “male” nor “female” by society at large and are officially recognized as a third gender in law. While afforded this recognition, most Hijra have a low social standing and their roles and importance are largely in response to changing structures of society as a whole (Taparia, 2011).

“Psychological Androgyny”

All of the pre-1985 papers and books within this review have “psychological androgyny” as their main descriptor. “Psychological androgyny” is presented in opposition to sex-typed roles and does not refer to a gender identity as such, but more a series of personality traits (Robinson & Green, 1981). The psychologically androgynous person is described as a person who displays high levels of typically “masculine” and “feminine” traits, which serve to benefit the individual in social situations by providing greater flexibility in behavior (Bem, 1974). Although later research on the stigma of transcending expected gender roles suggests the disadvantages outweigh any social gains, especially in relationships between younger people (Grossman & D’Augelli, 2006; Lee & Troop-Gordon, 2011).

Bem described in her 1974 paper that “rigid sex-role differentiation has already outlived its utility” (Bem, 1974, p. 162). Further to this, her study detailed her development of a “Sex-Role Inventory.” This measure of gender stereotypes and roles was developed by surveying 100 Stanford University students in regards to what they feel are “ideal,” “masculine,” and “feminine” traits. These desirable traits for each gender were used as the basis for questions within Bem’s Sex-Role Inventory.

Most of the papers in this review described “androgyny” as a concept rather than a gender identification but did go on to describe a homogenous group using the answers from the continuous variables of “masculine” and “feminine.” Scores from psychometric tests were divided into categories at certain pre-selected levels. For example, Wiggins and Holzmuller (1978) described various groups as “masculine-stereotyped,” “female-stereotyped,” and “androgynous.” Participants were placed into one of the three categories depending on the balance of “masculine” and “feminine” answers they gave to a set of pre-defined questions. Similarly, Gilbert (1981) utilizes groupings developed in Spence et al. (1975) to describe four distinct and homogenous groups – “Androgynous” (high in masculine traits and high in feminine traits), “Masculine” (high in masculine traits and low in feminine traits), “Feminine” (low in masculine traits and high in feminine traits), and “Undifferentiated” (low in masculine traits and low in feminine traits). Fitzpatrick, Euton, Jones, and Schmidt (2005), introduced “cross-gender” as a category, which described those displaying strong traits of the opposite gender to the one assigned at birth.

The concept of “psychological androgyny” (Ward, 2000) certainly led to a paradigm shift away from gender as dichotomous (“male” and “female” as opposites with no overlap) and instead viewed “masculinity” and “femininity” as independent dimensions of personality which can be traits of a single person in equal or unequal measure (Robinson & Green, 1981). This also broke down the deterministic nature of “being male/female” and furthered ideas of gender being, at least in part, socially constructed.

However, there are other issues with the concept of the Sex-Role Inventory. The concept of androgyny still depends upon the binary of “masculine” and “feminine” (Bem, 1974). The ratings given after the test is complete still gives a binary score with a “masculine” and “feminine” rating. The test is still created using a list of socially acceptable “masculine” and “feminine” traits. The difference between these “masculine” and “feminine” traits would need to exist in society in order for the test to work. While representing a good starting point for the study of “non-male” and “non-female” identities, “psychological androgyny” moved to become outdated as the concept of gender identity was discovered to be more multi-faceted and complex than a psychometric test can easily describe.

“PoMoSexuality”

In the introduction to their 1997 book of the same name, Queen and Schimel state that the term “PoMoSexuality” (a shortened term for “postmodern sexuality”) was not intended as a new descriptor, but a tool by which to examine the emerging boundaries of gender and sexuality at that time (Queen & Schimel, 1997). Described by Queen and Schimel (1997) as the “queer queers, who can’t seem to stay put within a nice simple identity,” this book of the same name uses the term “PoMoSexuality” as a starting point for the breaking down of gender’s borders and comments on the other side of homosexuality and transgenderism, the side that doesn’t wish to conform to the normative boundaries set out by society. Those who chose to take on the label often did so as a protest against labels themselves. By identifying as “PoMoSexual,” the individual was choosing to state their identity is not fixed or polarized. It offered the freedom not to commit to a certain label (The Center for Sexual Pleasure & Health, 2018). Queen and Schimel described how the term was a reaction against the assumptions of the LGBT + community about what it means to be queer – “We react against these assumptions in the same way that in the art world ‘Postmodernism’ was a reaction against Modernism.” The term was never widely used, although it does capture a moment when the boundaries of gender and sexuality were starting to disintegrate.

Whilst the ideas behind “PoMoSexuality” were certainly along the lines of gender diversity, the word itself was never totally appropriate to define a specific gender identity. “PoMoSexuality” is a concept, one which does break down the old ideas of “male” and “female” but has a range which also describes sexuality without borders as well. Using “PoMoSexuality” itself as a gender diverse identifier would be erroneous. Instead, it is listed here to show a moment in scholarly work where the idea of people choosing to live outside of the gender dichotomy was explored as part of a wider project to break down labels in society. Certainly, Queen’s book captures an idea that gender within the LGBT movement at the time was still a notable feature and there were already voices stating that their identity did not fit either of the “male” or “female” options.

“Gender Queer” or “Genderqueer”

In the 1990s, the cultural shift towards the use of transgender instead of transsexual as a wider umbrella term made room to include identities other than strict binary “male” and “female” identifying people (Smelser & Baltes, 2001). In Read my lips: Sexual subversion and the end of gender (Wilchins & Serano, 1997), the word “genderqueer” is used to describe any transgender person who has not and is not planning to undergo surgery. Examples given were “crossdressers,” “stone butches,” “intersex people,” and “drag people.” “Gender queer” (most often now written as a single word in later texts) started to appear within the queer and transgender lexicon with a more established meaning later in the 90s (Ekins & King, 2006; Halberstam, 1998). Here, it started to describe somebody who felt their gender lay outside of the binary, between “male” and “female” or towards one specific binary identity but not quite totally identifying with it.

The main descriptive features of many papers and books found within this review can be reduced to a few clear elements that are present in one form or another in all text. First is that “genderqueer” is a diverse term that is not able to be classified simply as “male” or “female” and second is that it is both a felt inner experience and a conscious expression of a “non-male” and “non-female” identity. Much of the material notes the description of “genderqueer” as rebellious in nature. For example, Stachowiak (2017) describes how genderqueer presents a “challenge” to the gender system, while Bradford et al. (2018) describe “genderqueer” identities as a rebellion against the master narrative. This distinction of a rebellious nature fits with the early narratives of queering gender by breaking down the heteronormative narrative (Richards, Bouman & Barker, 2017) and forms a picture of “genderqueer” as partly a considered disagreement with rigid heteronormative gender categories. This distinction of an act rather than just an identity is one early writer on the subject featured heavily (Girshick, 2008; Nestle, Howell, & Wilchins, 2002; Wilchins & Serano, 1997).

However, the political aspect of being “genderqueer” is not a homogenous one as scholars do not always add this element to their description, instead of using the term simply as an umbrella for any gender outside of “male” and “female” (Bockting, 2008; McGuire, Beek, Catalpa, & Steensma, 2018). This lack of description for the active and rebellious nature of “genderqueer” could be argued to largely render the identifier indistinct from other terms such as “non-binary,” the other leading term for such gender identities. While early use of the term emphasized the active un-doing of heteronormative gender structure (Wilchins & Serano, 1997), this element is lost in some later papers that do not describe the meaningful contrary nature of the identity.

While some papers in the review either mentioned alternative terms for “genderqueer” identities (Bockting 2008; Bradford et al., 2018) some of them depended upon “genderqueer” as the main identifier with little or no reference to other label options (Budge, Rossman, & Howard, 2014; Corwin 2017; Stachowiak, 2017). Some, for example, McGuire et al. (2018), uses “non-binary” and “genderqueer” within the same paper with seemingly no clear or obvious distinction between them. While the abstract sticks to “non-binary” as an identifier, the rest of the paper focuses mainly on “genderqueer.”

A feature notable of the material found under the genderqueer search term is that it is largely qualitative in nature. The one example of a quantitative study in this review McGuire et al. (2018), demonstrates the complexity of this. Aiming to produce a new gender tool that can describe the multi-dimensional nature of gender beyond “male” and “female,” McGuire et al. (2018) produced the Genderqueer Identity Scale (GQI), a tool to actively represent the diversity of gender expression. However, while seemingly a good tool to aid the scholar in the definition of genders beyond “male” and “female,” the moment by moment situational expressions and negotiations of an individual’s gender identity is not able to be captured in a meaningful way as the questions assume a static sense and expression of gender.

Non-Binary

Shortly after “genderqueer” started to be widely used, the term “non-binary” also started to appear (Richards et al., 2017). One of the first mentions of the term “non-binary” within this review was in Richards and Barker (2015, The Palgrave Handbook of the Psychology of Sexuality and Gender – Chapter 10, Further Genders). This appearance of the identifier “non-binary” places it almost a decade away from the first appearance of “genderqueer” (Wilchins & Serano, 1997). The findings of the review seem to indicate that “non-binary” is a relatively recent term in scholarly work (Richards et al., 2016, 2017).

The description laid out in Richards and Barker (2015) describes “non-binary” identities in seven bullet points – no gender, incorporate aspects of both genders, are to some extent but not fully one gender, an additional gender, move between genders, move between multiple genders and disrupt the binary. This seven-point description is most often shortened to three clear points to describe non-binary identities as (1) between “male” or “female”; (2) closer to one gender than another, but not entirely “male” or “female”; and (3) outside of the binary system altogether. This three-point description is commonly used in one form or another to describe “non-binary” identities (Clark, Veale, Townsend, Frohard-Dourlent, & Saewyc, 2018; Darwin, 2017; Monro & Van der Ros, 2018; Richards et al., 2017).

Within the literature uncovered by this search, two different grammatical ways of reproducing the same word were used. Darwin (2017) chooses not to use a hyphen and instead writes the word as one – “nonbinary.” This agrees with the Merriam-Webster Dictionary spelling (Nonbinary, 2018), which is arguably the best-known American dictionary. By contrast, the Oxford English Dictionary does include the hyphen (Non-binary, 2018). The majority of scholars within this review also choose to hyphenate (“non-binary”) in-line with both United Kingdom (UK)-based English and science in general, both of which are more reluctant to drop the hyphen (Nichol, 2019). Whilst this may seem like a small issue, modern scientific databases are used extensively for gathering background research on a topic. Therefore key papers, such as Darwin’s, may be overlooked as they do not follow the convention set out by other scholars.

There are also differences in the noun chosen to proceed “non-binary.” In the literature within this search, there appear to be three main options used. The first is “person” or “individual(s).” For example, Taylor, Zalewska, Gates, and Millon (2018) state as part of their abstract, “As non-binary individuals are increasingly presenting at UK gender identity clinics and requesting medical interventions…” (p. 1). Other scholars have used “gender” as the noun, such as Clark et al. (2018) who write “non-binary gender.” Some extend this and proceed with “gender identity” or simply “identity,” for example, Monro and Van Der Ros (2018). There is an exception to all three nouns in O’Shea (2018), who uses the noun “transsexual” after the word “non-binary.” However, this is a very nuanced use as O’Shea’s work is a self-ethnography and so “non-binary transsexual” would be considered a use specifically to their situation.

There seems to be no agreement on the ideal proceeding noun both within scholars and even within single pieces of work (see Clark et al., 2018), who use both “personal/individual(s)” and “gender” as proceeding nouns within the first three paragraphs alone. “Person” or “individual” proceeding nouns could be described as linguistically correct (e.g., “male/female person” or a “cis-individual” are acceptable terms). “Gender” may also be linguistically correct as, in the same fashion, a male/female may be referred to as the “male gender” or “female gender.” However, an issue with the use of “gender” is that in doing so, it is suggesting that “non-binary” is itself a gender, a third option to “male” and “female,” which many who identify this way may disagree with. The preferable term could be “non-binary gender identity,” which accurately refers to a gender identity that is not considered to be binary.

GQ/NB or NBGQ

From 2014 onwards, “genderqueer” and “non-binary” become the main descriptors. Many papers also detail other descriptions, such as “genderfluid,” “genderfuck,” and “polygender” although most still employ either “genderqueer” or “non-binary” as their main umbrella term. Some recently published papers (Broussard, Warner, & Pope, 2018; Koehler et al., 2018) have used both identifiers as the main umbrella term, sometimes using an initialism such as GQ/NB (non-binary, genderqueer).

The difference between the two has been contested and debated since both terms converged onto the gender identity landscape. Outside of academia, some commentators view “genderqueer” as more than an identity, but a statement against the gender system and places the identifier within the queer umbrella (Tobia, 2007). In contrast, “non-binary” identities have been described as apolitical and more a statement of identity, and thusly linked more with those who primarily identify as trans (Quoracom, 2018). Others suggest that “non-binary” is a specific identifier underneath the “genderqueer” umbrella (GENDERQUEER AND NON-BINARY IDENTITIES, 2018). This debate has not been detailed or explored within research with most articles and books choosing either one identifiers or occasionally an amalgamation of both, such as GQ/NB (Lykens et al., 2018). More recent articles also include both identifiers, negating the need to choose one as a defining umbrella term (Nicholas, 2018).

The hierarchy of both words is equally a contested terrain that seems to have settled in an equal tie. While some papers, for example, Darwin (2017) describes “genderqueer” as an identity within the realms of “non-binary,” other authors in the review have used the two words interchangeably with little or no description to signify the choice of use. Richards et al. (2017) explicitly state that “genderqueer” has become a popular term outside of scholarly work and so it is included within the title of their book to reflect this equal weight with “non-binary” (p. 2). For the casual reader, there may be little issue with the interchangeability of these two words. For the scholar, the matter may need a resolution as keywords form a vital function in academia and a paper can succeed or fail depending upon the words used both within the title, body text, and keyword listings. Academic papers are now commonly searched for within databases, university libraries, and facilities such as Google Scholar that use keywords in the title, abstract, and body text to return results. Depending upon common forms of spelling or grammar in a paper could lead to a paper being missed in many searches as they do not contain a commonly used keyword but a lesser used alternative. For this reason, it seems many modern researchers include both terms until a resolution or alternative is settled on.

In addition, the importance of etymology cannot be overlooked. Language is not rigid or static and the etymology of a word can act as a small time-capsule, revealing the changing narratives and ideas relating to the object or action it describes. There are also points in time where words become “reclaimed” or equally fall from favor, creating the need for new words or definitions of existing words. The movement towards a single, alternative umbrella term may represent a moment of cohesion, where multiple ideas and words surrounding certain gender identity are grouped together with a similar concept of identities that are neither “male” nor “female.”

Vincent (2016) highlights the need for respect in the individual’s choice of other “genderqueer” or “non-binary” as their identity. Ultimately for the scholar, a single umbrella term may be of great use and as Vincent (2016) points out, the use of “genderqueer” and “nonbinary” have become used synonymously. This leaves the scholar with two options – to abbreviate and initialize both identifiers or to choose one over the other, but include a reasonable Defense for their choice.

Discussion

It is certainly no accident that a multitude of identities beyond the binary have sprung into the public consciousness as access to the internet has increased (Cover, 2018). It is in online spaces where those who feel their gender is not congruent with the binary have met, discussed, and co-created many of the terms listed in this article (Fraser, 2017). Identities, feelings, and experiences which may have always been present in society, but were repressed and experienced in isolation could have emerged with the ability to meet, discuss and collectively create lexical expressions with the use of the internet in a safe, non-stigmatising environment (Plummer, 2002). Scholarly work has reflected such terms and the term used is often down to the researcher’s preference, discretion or the time at which the paper was written. The two leading umbrella terms to emerge in this search are “non-binary” and “genderqueer.” However, these are not a good “one size fits all” and as research continues, issues with these as overarching terms are emerging.

“Genderqueer” has often been associated with a political stance against gender and a political bent, but today is more readily used as an umbrella for any identity outside of “male” and “female.” The inclusion of “queer” within the word can have negative connotations for some. Those who have previously experienced the word “queer” as a verbal attack may have strong negative experiences related to the negative use of the word and as such, may feel uncomfortable labeling themselves as “genderqueer” (wiseGEEK, 2019). The past use of the word “queer” was also a slur aimed primarily at the homosexual community which has been reclaimed instead to mean a sense of pride, such as the 1990s activist group “Queer Nation,” who used the word to both shock and reclaim its use for the homosexual community (Gray, 2009). Since, there has been a widening of the meaning to be an opposition to heteronormativity and the celebration rather than degradation of difference (Gamson, 1995), although the term may not suit everybody and some may see their gender as a personal or even medical matter, especially if the person holds multiple minority identities and do not experience social privileges such as being white, middle-class, highly educated or lacking a visible disability (Richards et al., 2017).

“Non-binary” also has a number of limitations in its use. The word can give the impression of somebody “in the middle” of male and female, although for many this strict definition is not the case. The very nature of the word also denotes the existence of a binary from which the gender diverse person is separate from. In some cases, a gender diverse person may disagree with the word “non-binary” as it means their gender identity is still described in relation to the binary – the binary must exist for their own identity to exist. Moreover, the prefix “non” can be seen to construct a sense of “other” (Boréus, 2006). “Non-binary” sets up the binary up as the norm which those who don’t identify this way are not an identity in itself, but something other than the norm. Being “the other” devalues the experience of those who do not feel they identify with the binary and problematizes them within gender discourse (Boréus, 2006). An example of this would be describing a homosexual as “non-heterosexual,” which places the dominant power in society as the norm and “others” the less socially powerful by the use of an unintentionally destructive discourse (Rothmann & Simmonds, 2015).

Over the period of this review, it is clear that gender has come to be seen as heterogeneous in nature rather than a dichotomy of two opposites. Identities that are not binary in nature have pushed the boundaries of what it means to be trans. They have also changed the nature of the trans community from a group with identities mirroring that of wider society into a more personalized and flexible set of identifiers. This varied nature to identities outside of the binary leads to difficulties in summing-up such a group in one easy term. There may also be the question as to why a single umbrella term is needed when gender identities outside of the binary vary so much from person to person. However, the needs of the scholar are different to the individual – words are not personally descriptive, but a tool for gathering information on one subject under an umbrella term that is recognizable as a definable group in society and an aid to communication research on this group to other researchers. For the researcher, a common name would mean not only easier searching for past work on the subject within scholarly databases, but also a common language with which to research and discuss a varied group, which nonetheless has a common factor – not identifying as “male” and “female.” Having the language to specify this group and communicate research is currently a task complicated by multiple identifiers and seemingly little to distinguish between them. Aside from the practical issues of search terms, a suitable academic term is needed which both accurately describes identities that are not “male” and “female,” which reflects the group it describes in a positive light and which also has approval, if not widespread use, within the community.

An emerging term in many areas of scholarly work is the term “gender diverse.” An early use of “gender diverse” can be seen in the Australian Journal of Human Rights in 2009. Although this article was outside the scope of the review, Winter (2009) describes “gender diverse” as “a term that recognises and celebrates that all people express a gender identity and that gender identity and expression are not necessarily linked to a person’s sex.” This broad description suggests a term which is inclusive of all gender identities beyond that of a person’s assigned sex at birth and breaks down the notion of two single and fixed genders. More recently, Hines and Taylor (2018) used several identifiers (including “non-binary” and “genderqueer”) in their recent book, but in addition, gave the description for “gender diverse.” Hines writes, “a gender diverse person does not conform to their society’s norms or values when it comes to their gendered physicality, gendered identity, gender expression or combination of those factors.” This definition suggests that “diversity” relates to those with identities beyond those of binary gender markers, suggesting all gender identities beyond the recognizable identities of “male” and “female” could fall under the “gender diverse” umbrella.

Some organizations and institutions outside of academia have also embraced “gender diverse” as a term for those between or outside of the gender binary. In the UK, trans charities such as Gendered Intelligence (http://genderedintelligence.co.uk) and the youth organization Mermaids (https://www.mermaidsuk.org.uk) have both adopted “gender diverse” as a term within their literature. In 2017, Division 44 of the American Psychological Association changed its name from the Society for the Psychological Study of LGBT Issues to the Psychology of Sexual Orientation and Gender Diversity to reflect the increasing diversity beyond “male” and “female.” Both Australia and New Zealand also now have “diverse” as a legal gender option, also in recognition that strict “male” and “female” options have become too limiting for an increasingly diverse population. The Australian Passports have a “diverse” option and is marked as an “X” rather than the norms of “M” and “F.”

The use of gender diverse has been increasing. However, the term has also very often been used as a way of “summing up” all gender identities outside of binary trans and to a certain extent, has been used to “cover all bases” rather than providing a specific description. For example, many of the papers found in the search for this review (which were rejected for not meeting the criteria as the papers were predominantly about binary trans issues) use “gender diverse” alongside the word “transgender” (e.g., Gower et al., 2018; Mizock & Hopwood, 2018). Some also abbreviated this from “transgender and gender diverse” to simply “TGD.” No specific distinction was made between the two identifiers in many of these papers and the studies generally diluted experiences of those outside the binary by assuming the “transgender and gender diverse” community was a homogenous group. Of course, another limitation could be a lack of homogeneity within “gender diverse” people too.

The use “gender diverse” as a “catch-all” term for genders outside the binary, but with no further description or consideration to difference has two major limitations. First, it sets apart the two descriptions – “transgender” and “gender diverse” – and makes an assumption that “gender diverse” identities are distinct from “transgender” identities, which for many people is not the case. For example, Koehler et al. (2018) reported that 20% of the transgender community do not identify as “male” or “female,” and so a sizable part of the transgender community could be described as “gender diverse.” Second, setting apart those who do not identify on the binary in this way implies they are “other” to the dominant transgender narrative and excluding their lived experiences from the transgender narrative, further “othering” identities that are not part of the binary. While those who identify outside of the binary do often identify as transgender as well, a clear distinction must be made in research specific to issues to the dominant binary transgender narrative as the experiences of those outside of the binary may differ. In a similar way, the differences in the experience of those who do identify with the binary should also be acknowledged and not diluted with a less dichotomous view of gender. The acknowledgment of areas where the two groups are not homogenous would serve to benefit both groups.

If the term “gender diverse” is used more specifically as a sub-group of the trans umbrella, then it could be used in a positive way to summarize identities outside of the binary. The Oxford English Dictionary defines “diverse” as “Showing a great deal of variety. Very different” (Diverse, 2018). Therefore, a person who holds a diverse gender identity would, by definition, express or experience more than just a “male” and “female” identity, but a combination or lack of these identities. It could be argued that experiencing your gender purely as “male” or “female” does not show variety and is thus not “diverse” in nature.

The word “diverse” is generally thought of as a positive word and has a widespread interpretation of valuing difference (Gerteis, Hartmann, & Edgell, 2007). A conceptualization of gender identities outside of “male” and “female” is a challenge to many in society. The word “diversity” may help to conceptualize gender as a multifaceted and positive concept rather than binary and “other” in nature. Although of course there is a further limitation in the possibility of creating the assumption of homogeneity within “gender diverse” identifying people. The experience of one person who identifies outside of “male” and “female” could be vastly different from another. “Gender diverse” also must be understood as a functional umbrella term for the use of easily summing up a group of identities, but the emphasis must still remain on the individual being free to choose the specific identifier under that umbrella which feels right for their own identity.

This review has a number of limitations. First, many terms for identities other than male and female have been excluded as they appear in papers where binary transgender issues dominate the study. Furthermore, with gender identity embodying a complex range of characteristics and meanings for the individual, it is natural that beyond the key terms described in this article, there are many sub-terms used to identify a more personal and nuanced description. A great deal of the papers and books in this review contain more than one term and in some cases, lists of various different identifiers both generated by the participant and by the researcher. These secondary terms constitute a long list of possible identities and identifiers. A detailed description of these identifiers was not generally included within the papers and books and mostly they were generated in response to open questions to participants relating to gender identity. The main umbrella term chosen, which did contain a description, was generally the choice of the researcher. This suggests that further research could investigate which terms are most used within the community itself rather than within scholarly work and question whether researchers are using the best terms to describe this population. Opinions regarding how the community feel about scholars’ choice of terms would also be an important future research project as many key debates and terms may be missing from scholarly work.

Conclusion

For the last 50 years, different terms have been used to describe people who identify between, outside and beyond of the gender binary. The earliest term found in this review was “psychological androgyny,” although “Two-Spirit,” which wasn’t found in this review until later, is described as a term emerging earlier within Indigenous American culture. In parts of the Indian subcontinent, the “Hijra” people have blurred the line between male and female. In the late 90s, Queen and Schimel’s theoretical stance in their book “PoMoSexual” demonstrated how the generally accepted bounds of male and female were being broken down. Not long after, the word “genderqueer” appeared within scholarly work, followed later by “non-binary.” Both terms are now leading umbrella terms for those who feel their gender identity is neither male nor female.

Both “genderqueer” and “non-binary” contain complications for certain sections of the community they represent, and so a suggested alternative umbrella term for academic use is “gender diverse.” This term is a descriptor for identities that are not “male” or “female” and is intended as an overarching term under which individuals within the population remain free to choose their own identifier. Future research could gather data relating to the identifiers used by the community and gauge opinion on a suitable umbrella term. The need to research suitable terms is not only an important establishing step towards vitally needed work in this area, but it must also be a task conducted with sensitivity to the minority group in question and wherever possible, with direct input from the community itself.

Funding Statement

This study is funded by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care East Midlands (CLAHRC EM). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.

Declaration of interest

The authors have no other potential conflict of interests to declare.