Gender is a range of physical, mental, and behavioral characteristics distinguishing between masculinity and femininity.[1][2][3] Depending on the context, the term may refer to sex (i.e. the state of being male or female), social roles (as in gender roles), or gender identity.[1][2][3][4]
Gender studies is a branch of the social sciences. Sexologist John Money introduced the terminological distinction between biological sex and gender as a role in 1955. Before his work, it was uncommon to use the word "gender" to refer to anything but grammatical categories.[1][2] However, Money's meaning of the word did not become widespread until the 1970s, when feminist theory embraced the distinction between biological sex and the social construct of gender. Today, the distinction is strictly followed in some contexts, especially the social sciences[5][6] and documents written by the World Health Organization (WHO).[4] In contrast, for many contexts, including some areas of social sciences, the meaning of gender has expanded to include "sex" or even to replace the latter word.[1][2] Although this gradual change in the meaning of gender can be traced to the 1980s, a small acceleration of the process in the scientific literature was observed when the Food and Drug Administration started to use "gender" instead of "sex" in 1993.[7] "Gender" is now commonly used even to refer to the physiology of non-human animals, without any implication of social gender roles.[2]
In the English literature, the trichotomy between biological sex, psychological gender, and social sex role first appeared in a feminist paper on transsexualism in 1978.[2][8] Some cultures have specific gender-related social roles that can be considered distinct from male and female, such as the hijra of India and Pakistan.
While the social sciences sometimes approach gender as a social construct, and gender studies