non·bi·na·ry [?nän'bin?re] ADJECTIVE non-binary (adjective) 1. not relating to, composed of, or involving just two things. "Aristotelian ontology is nonbinary on the second level in that it allows for degrees of being" * denoting or relating to a gender or sexual identity that is not defined in terms of traditional binary oppositions such as male and female or homosexual and heterosexual. "nonbinary people are vastly underrepresented in the media"