sex.

Borrowed from English sex (“sex; sexual activity”), from Middle English sexe (“sex; distinction between male and female”), from Old French sexe (“sex, gender; genitals”), from Latin sexus (“sex, gender; division into males and females”), from Proto-Italic *seksus, usually traced to Proto-Indo-European *séks-u-s, from Proto-Indo-European *sek- (“to cut, sever, divide”). The original underlying sense is therefore generally interpreted as a “division” or “section”, referring to the division into sexes. The English word originally referred principally to biological sex or the distinction between males and females. Its use for sexual intercourse and sexual activity is a later semantic development. Compare Norwegian Nynorsk sex, Danish sex, Swedish sex and German Sex, parallel modern borrowings ultimately from Latin sexus, as well as French sexe, Spanish sexo, Portuguese sexo and Italian sesso.