Effeminacy or male femininity is the embodiment of feminine traits in boys or men, particularly those considered untypical of men or masculinity. These traits include roles, stereotypes, behaviors, and appearances that are socially associated with girls and women. Throughout history, men considered effeminate have faced prejudice and discrimination. Gay men are often stereotyped as being effeminate, and vice versa. However, femininity, masculinity, and other forms of gender expression are independent of sexual orientation.

Femininity is a set of attributes, behaviors, and roles generally associated with women and girls. Femininity can be understood as socially constructed, and there is also some evidence that some behaviors considered feminine are influenced by both cultural factors and biological factors. To what extent femininity is biologically or socially influenced is subject to debate. It is conceptually distinct from both the female biological sex and from womanhood, as all humans can exhibit feminine and masculine traits, regardless of sex and gender.