Gaydar is the intuitive ability to determine whether another person is Gay (homosexual), or straight (heterosexual). The function of "gaydar" relies on non-verbal sensory information and intuitions. These include the sensitivity to social behavior and mannerisms: for example; a sensitivity to flamboyant or overt rejection of traditional gender roles (including occupation and grooming habits).

The idea of gaydar is complicated by gay men not acting in a stereotypical fashion and also by metrosexual men who have a heightened aesthetic sense, regardless of sexuality and exhibit a lifestyle, spending habits and concern for personal appearance traditionally likened to those stereotypes of a fashionable, urban, gay man.