'intersex' is formed in English from the prefix 'inter-' meaning 'between' (Latin 'inter') + 'sex' (from Latin 'sexus'), literally signalling 'between sexes' or 'among sexes'.

The term developed in English in the 20th century in medical and social contexts to describe bodies that do not fit binary categories; earlier terminology included 'hermaphrodite' (from Greek 'hermaphroditos'), which has largely fallen out of professional and respectful use.

Initially used primarily in medical descriptions to denote ambiguous or atypical sex characteristics, the term has evolved to be used both clinically and as an identity label embraced by some people and communities.