Feminist concerns about the social representation of sex, sexuality, and sexual organs have included analyses of their representation both in dictionaries and in medical texts. Drawing on feminist and social constructionist work, we analysed entries for ‘clitoris’ and ‘vagina’, using entries for ‘penis’ as a comparison, in 12 medical and 16 English language dictionaries. Both ‘vagina’ and ‘clitoris’ were overwhelmingly defined by their location in a female body, whereas the penis was defined in terms of function. Description of sex/sexuality was frequently omitted from both vaginal and clitoral definitions, and women's genitals continue to be defined in relation to an implicit penile norm. Three assumptions informed these definitions – that female sexuality is passive (and male sexuality active), that women's genitals are ‘absence’ (and men’s are ‘presence’), and that genitals are used for heterosexual sex – explicitly coitus. We suggest that these definitions present, as natural biological fact, common sense sexist and heterosexist assumptions about female and male bodies and sexualities.