Sex
late Middle English (denoting the two categories, male and female): from Old French sexe or Latin sexus .
wiktionary
From Middle English sexe(“gender”), from Old French sexe(“genitals; gender”), from Latin sexus(“gender; gender traits; males or females; genitals”), from Proto-Italic *seksus, from Proto-Indo-European *séksus, from *sek-(“to cut, cut off, sever”), thus meaning "section, division" (into male and female).
Usage for women influenced by Middle French le sexe(“women”) (attested in 1580). Usage for third and additional sexes calqued from French troisième sexe, referring to masculine women in 1817 and homosexuals in 1847. First used by Lord Byron and others in English in reference to Catholic clergy. Usage for sexual intercourse first attested in 1900 (in the writings of H.G. Wells).
From sect.
etymonline
sex (n.)
late 14c., "males or females collectively," from Latin sexus "a sex, state of being either male or female, gender," of uncertain origin. "Commonly taken with seco as division or 'half' of the race" [Tucker], which would connect it to secare "to divide or cut" (see section (n.)).
Secus seems the more original formation, but it is strange that the older texts only know sexus. The modern meaning of sectiō 'division' suggests that sec/xus might derive from secāre 'to sever', but the morphology remains unclear: does sexus go back to an s-present *sek-s- 'to cut up', or was it derived from a form *sek-s- of the putative s-stem underlying secus? [Michiel de Vaan, "Etymological Dictionary of Latin and the other Italic Languages," Leiden, 2008]
Meaning "quality of being male or female" first recorded 1520s. Meaning "sexual intercourse" is attested by 1906; the meaning "genitalia" is attested by 1938. Sex appeal is attested by 1904.
For the raw sex appeal of the burlesque "shows" there is no defense, either. These "shows" should be under official supervision, at the least, and boys beneath the age of eighteen forbidden, perhaps, to attend their performance, just as we forbid the sale of liquors to minors. [Walter Prichard Eaton, "At the New Theatre and Others: The American Stage, Its Problems and Performances," Boston, 1910]
Sex drive is by 1918; sex object by 1901; sex symbol by 1871 in anthropology; the first person to whom the term was applied seems to have been Marilyn Monroe (1959). Sex therapist is from 1974.
sex (v.)
1884, "to determine the sex of," from sex (n.); to sex (something) up "increase the sex appeal of" is recorded from 1942. Related: Sexed; sexing.
