1939, "clumsy, careless, sloppy; a name applied to anything that is dirty or in bad shape," U.S. Army Air Corps slang, a word of unknown etymology. Origins among cadets in Texas suggest a possible connection to Mexican Spanish rancho (see ranch (n.)), which had connotations of animal filth by 1864; raunch was an old alternative English spelling of ranch. Sense of "coarse, vulgar, smutty" is from 1967. Related: Raunchiness.
"of or imparting filth," early 15c. metathesis of dritty "feculent; muddy" (late 14c.), from dirt + -y (2). Sense of characterized by dirt, unclean" is from 16c. Meaning "smutty, morally unclean" is from 1590s. Of colors, from 1690s. Sense of "not streamlined; rough, untidy, or imperfect" is by 1925. Of atomic bombs, "producing much radioactive fallout," by 1956.
Dirty linen "personal or familial secrets" is first recorded 1860s. Dirty work in the figurative sense is from 1764; dirty trick is from 1670s. Dirty joke is by 1856. The dirty look someone gives you is by 1923; dirty old man "superannuated lecher" is from 1932. Related: dirtiness.
1660s, joque, "a jest, something done to excite laughter," from Latin iocus "joke, jest, sport, pastime" (source also of French jeu, Spanish juego, Portuguese jogo, Italian gioco), from Proto-Italic *joko-, from PIE *iok-o- "word, utterance," from root *yek- (1) "to speak" (cognates: Welsh iaith, Breton iez "language," Middle Irish icht "people;" Old High German jehan, Old Saxon gehan "to say, express, utter;" Old High German jiht, German Beichte "confession").
Originally a colloquial or slang word. Meaning "something not real or to no purpose, someone not to be taken seriously" is from 1791. Black joke is old slang for "smutty song" (1733), from use of that phrase in the refrain of a then-popular song as a euphemism for "the monosyllable." Lithuanian juokas "laugh, laughter," in plural "joke(s)" probably is borrowed from German.
"lewd, indecent" recorded from 1840 (in the form blueness, in an essay of Carlyle's); the sense connection with the color name (see blue (adj.1)) is unclear, and is opposite to that in blue laws (q.v.). John Mactaggart's "Scottish Gallovidian Encyclopedia" (1824), containing odd words he had learned while growing up in Galloway and elsewhere in Scotland, has an entry for Thread o'Blue, "any little smutty touch in song-singing, chatting, or piece of writing." Farmer ["Slang and Its Analogues Past and Present," 1890] offers the theory that this meaning derives from the blue dress uniforms issued to harlots in houses of correction (from c. 1600), but he writes that the earlier slang authority John Camden Hotten "suggests it as coming from the French Bibliothèque Bleu, a series of books of very questionable character," and adds, from Hotten, that, "Books or conversation of an entirely opposite nature are said to be Brown or Quakerish, i.e., serious, grave, decent."