Table 2.

Examples of how to redefine terms associated with sex diversity and variability to be operational, precise, and inclusive.

Historically used terminology	Updated terminology	Justification
Biological sex	Sex	“Biological sex” conflates the biology of sexed characteristics as determined and immutable. It has also been used to incorrectly draw distinctions between the genetic, molecular, physiological, and behavioral (nominally “sex”) from the psychological, ecological, and sociological (nominally “gender”) aspects of sex and gender diversity when, in fact, these elements are highly intertwined in unique and specific ways. In our integrative framework, sex goes beyond what is classically considered biological, thereby making the term “biological sex” overconstrained.
“Male hormones” (i.e., when referring to effects of androgens) and “female hormones” (i.e., when referring to effects of estrogens or progestins)	Androgens, estrogens, and progestins	This terminology presents a false binary that these hormones only have sex-specific functions while downplaying the role of other hormones. In reality, these hormones are functionally important in all sexes.
Masculinization (i.e., when referring to effects of androgens) or feminization (i.e., when referring to the effects of estrogens or progestins)	Androgenization (androgenic), estrogenization (estrogenic), or progestinization (progestigenic)	Using masculinizing/feminizing terminology in broad reference to outcomes of endocrine signals implies androgens, estrogens, and progestins only have sex-specific functions, when in reality, these hormones are relevant for all sexes. This terminology can be expanded to other molecules that have roles in sexual differentiation, such as oxytocin (oxytocinergic).
Sex determination	Gonadal determination	By definition, “sex determination” refers to a mechanism that determines the sex category of an individual, meaning all sex-associated traits are determined by one such mechanism. Thus, this term forgoes the multidimensional, multimodality of sex and continues the conflation of sex as ultimately originating from a singular process, reinforcing an essentialist binary operationalization.
Sex differences	Sex variability; subtyped: sex differences, sex similarities	As an umbrella term to describe sex, “sex differences” reinforces the search for discrete, binary biological variation between sexes, when in reality, there are differences and similarities across sex categories. “Sex variability” better encompasses the range of possible outcomes and sex-associated phenomena to study, used in conjunction with “sex differences” and “sex similarities” in specific comparisons.
Sexual dimorphism or sexual polymorphism	Sexual heteromorphism; subtyped: sexual monomorphism, dimorphism, multimorphism	“Sexual dimorphism” is the primary categorization of sex variable morphs, due in part to its prevalence in the majority of animal species studied, but imprecise application of the term can confuse, erase, or hide intraspecies sex variable phenotypes. Instead, sexual heteromorphism should be used as the overarching category for multiple morphs within a species that relate to sex, and subtyped in appropriate contexts. This terminology encourages contextual specificity. For example, traits at one biological scale may be monomorphic, and another dimorphic. This approach forgoes the implied lack of overlap in traits between sex categories and appropriately emphasizes that there can be multiple modes in trait value within and across sexes (Anderson and Renn, 2023). We suggest the use of multimorphism when referring to more than two, as polymorphism has other uses in the biological sciences that may confuse rather than clarify.
Sex role reversal (i.e., in reference to a specific behavior or set of behaviors)	Behaviors that coincide within a population	This terminology assumes a standard of “typical” sex roles, which is misleading and highlights and perpetuates biases for how norms are defined.

Examples of how to reframe commonly used terminology in research to improve operationalization, precision, and inclusivity. As an exercise, we encourage readers to consider the following questions: 1) Where does this term come from? (i.e., what is the historical basis of this term; does it originate from a false dichotomy that is being perpetuated in some way?); 2) Is this term inclusive?; 3) Is this term precise or used vaguely?; 4) Is this term operationally defined in the text and is the definition consistent throughout?