Etymology of "Gay"
March 15, 2008 / by lunarhunk

On a comment in one of his blogs, Martin asked me to look into the etymology of the word gay and how it came to be connected as a reference to homosexuals. So, this should be helpful:

1178, "full of joy or mirth," from O.Fr. gai "gay, merry," perhaps from Frank. *gahi (cf. O.H.G. wahi "pretty"). Meaning "brilliant, showy" is from c.1300. OED gives 1951 as earliest date for slang meaning "homosexual" (adj.), but this is certainly too late; gey cat "homosexual boy" is attested in N. Erskine's 1933 dictionary of "Underworld & Prison Slang;" the term gey cat (gey is a Scot. variant of gay) was used as far back as 1893 in Amer.Eng. for "young hobo," one who is new on the road and usually in the company of an older tramp, with catamite connotations. But Josiah Flynt ["Tramping With Tramps," 1905] defines gay cat as, "An amateur tramp who works when his begging courage fails him." Gey cats also were said to be tramps who offered sexual services to women. The "Dictionary of American Slang" reports that gay (adj.) was used by homosexuals, among themselves, in this sense since at least 1920. Rawson ["Wicked Words"] notes a male prostitute using gay in reference to male homosexuals (but also to female prostitutes) in London's notorious Cleveland Street Scandal of 1889. Ayto ["20th Century Words"] calls attention to the ambiguous use of the word in the 1868 song "The Gay Young Clerk in the Dry Goods Store," by U.S. female impersonator Will S. Hays. The word gay in the 1890s had an overall tinge of promiscuity -- a gay house was a brothel. The suggestion of immorality in the word can be traced back to 1637. Gay as a noun meaning "a (usually male) homosexual" is attested from 1971. --taken from the Online Etymology Dictionary (https://www.etymonline.com/index.php?term=gay)

According to the Dictionary of Word Origins by John Ayto (published by Arcade Publishing in 1990,
"gay [16th century] Englished borrowed gay from Old French gai, an adjective of uncertain origin cnnected by some with Old High German gahi [meaning] 'sudden, impulsive.' 'Happy' is its ancestral meaning, stretching back to Old French gai. The 20th-century sense 'homosexual,' which first cam to general usage in the 1950s, seems to have arison from an earlier American slang term gay cat, which originally denoted a young male tramp who was the companion of an older tramp. The implications of a homosexual relationship which this carried had led by the 1930s to the use of gay cat for any young male homosexual, and the application of gay to 'homosexual' was probably generalized from this." (p. 251)