Green’s Dictionary of Slang

(a) (orig. US) an intellectual or artist or musician.

[1865		‘Artemus Ward’ Among the Mormons in Complete Works (1922) 248: A young man who wore long hair, and had a wild expression in his eye [...] ‘He is an artist, papa. Here is one of his masterpieces’].
1880		Wkly News-Democrat(Emporia, KS) 18 June 1/4: The short-haired women and long-haired men [...] have taken possession of Chicago.
1902		Unionville Crescent (MI) 24 Oct. 7/4: Mr Longhair — Is the editor in? [...] I have a poem to submit to him.
1915		letter in L.A. Eve. Express 9 Mar. 12/2: You are a long-haired crowd that should not participate in govering a sane people.
1920		S. Lewis Main Street (1921) 281: I’m surprised to find you talking like a New York Russian Jew, or one of these long-hairs!
1932		G. Milburn ‘Some Kind of Color’ in Botkin Folk-Say 41: Get it out of your head that we make any money selling books to these long-hairs that read books [...] they go to the public library.
1940		S. Longstreet Decade 233: Art is subsidized by the longhairs, of whom Joyce said, ‘all p--k and no pence’.
1950		Dly Teleg. (Sydney) 31 Dec. 7/3: Melbourne saxophone player Ross Fusedale said ‘bodgies’ and ‘long hairs’ were barred from jazz. ‘There's no long hairs or drape sacks here,’ he said. ‘Jazz is a serious art form’.
1957		Mad mag. Jan.–Feb. 34: The following informative and educational article (designed to convert crew-cuts into long hairs).
1959		J. Osborne World of Paul Slickey Act II: Communists and queers! [...] Whores and longhairs!
1965		L. Haylen Big Red 187: ‘He’s got a string of degrees. [...] Been to Oxford!’ ‘Get rid of him,’ said Felix. ‘Look what the long hairs have done to the monetary system.’.
1976		R. Sabbag Snowblind (1978) 83: A grass-roots privacy-invasion force designed to intimidate long-hairs and indigents in transit.
1989		H. Rawson Dict. of Invective (1991) 239: longhair. A brainy person, especially an aesthete.
1998		J. O’Connor Salesman 156: That fuckin’ longhair you were talkin’ to. Who was he, anyway?
2001		S. King Dreamcatcher 8: Just another working-class longhair.
2023		R. Milward Man-Eating Typewriter 29: Co-sparkling alongside a Persian longhair.

(b) (US) a performer or aficionado of classical music.

1895		Star Trib. (Minneapolis, MN) 29 Apr. 5/4: It began with the coming of Oscar Wilde [...] Then came the eccentricities of the drama and song, and later the long hairs of music and literature.
1935		Charleston (WV) Daily Mail 27 June 8/8: A ‘long hair’ is a pit musician in legitimate theater.
1939		P.E. Miller Down Beat’s Yearbook of Swing n.p.: longhair : a symphony man; one who likes classical music.
1949		Music Library Association Notes Dec. 46: longhair: one who plays, appreciates, composes, or writes about concert music.
1989		H. Rawson Dict. of Invective (1991) 239: longhair. [...] a perfomer or devotee of classical or longhaired music.

(c) (US) a moral reformer.

1919		letter in Petaluma Argus-Courier (CA) 13 Feb. 2/3: I think about time someone made a proest about the ‘long-hair’ reformers who come [...] to Petaluma to make trouble.
1933		W.R. Burnett Dark Hazard (1934) 113: Some of the long-hairs want to get their names in the paper.