Table 1.

Definitions of selected terms and nomenclature

Term	Definition
Archaea	A domain of prokaryotes, single celled microorganisms
Dysbiosis	Non-homeostatic imbalance of microbiota that is associated with disease states19
Fecal microbiota transplant (FMT; fecal matter transplant; fecal transplant; bacteriotherapy)	Restoration of physiologic microbial community by means of transplanting microbiota via feces20
Metabolomics	Collection of metabolites (eg, short and medium chain fatty acids) produced by particular microbial community21 22
Metagenomics	Combined genomes of microbial community in its entirety (including viruses and fungi)18
Metaproteomics	Collection of proteins expressed by particular microbial community21 22
Metatranscriptomics	Collection of genes expressed by particular microbial community21 22
Microbiome	Collective genomes of microbial flora harbored by humans3 4
Microbiota	Symbiotic, commensal, and pathogenic microorganisms (microbial flora) harbored by humans3 4
Multi-omics	Integration of big data from “omic” technologies such as microbiomics, metagenomics, metatranscriptomics, metaproteomics, and metabolomics23
Pathobionts	Commensal bacteria with the potential to be pathogenic2
Prebiotics	Supplements containing substances that promote growth of supposedly beneficial microorganisms6 7
Probiotics	Supplements containing live microorganisms that can alter composition of microbiota and are supposed to provide health benefits to host6 7