early 14c., wan-towen, "resistant to control; willful," from Middle English privative word-forming element wan- "wanting, lacking, deficient," from Old English wan-, which was used interchangeably with un- (1), and is cognate with Dutch wan- (as in wanbestuur "misgovernment," wanluid "discordant sound"), Swedish and Danish van-, from Proto-Germanic *wano- "lacking," from PIE *weno-, suffixed form of root *eue- "to leave, abandon, give out." Common in Old and Middle English, still present in 18c. glossaries of Scottish and Northern English; this word is its sole modern survival.
Second element is Middle English towen, from Old English togen, past participle of teon "to train, discipline;" literally "to pull, draw," from Proto-Germanic *teuhan (source also of Old High German ziohan "to pull," from Proto-Germanic *teuhan; see tug (v.)). The basic notion perhaps is "ill-bred, poorly brought up;" compare German ungezogen "ill-bred, rude, naughty," literally "unpulled." Especially of sexual indulgence from late 14c. Meaning "inhumane, merciless" is from 1510s. Related: Wantonly; wantonness.
As Flies to wanton Boyes are we to th' Gods, They kill vs for their sport. [Shakespeare, "Lear," 1605]
"a wanton girl or woman," 1570s, slang, now obsolete, of obscure origin. Also as a verb, "to play the wanton, romp about." Related: Rigged; rigging.
1590s, "immodest, wanton, saucy," from French petulant (mid-14c.), from Latin petulantem (nominative petulans) "wanton, froward, saucy, insolent," present participle of petere "to attack, assail; strive after; ask for, beg, beseech" (from PIE root *pet- "to rush, to fly"). Meaning "irritable, manifesting peevish impatience" is by 1775, probably by influence of pet (n.2). Related: Petulantly.
"offensively abusive, wantonly irreverent, coarse, obscene," of persons, conduct, speech, etc., c. 1500, from obsolete noun ribald, ribaud "a rogue, ruffian, rascall, scoundrell, varlet, filthie fellow" [Cotgrave], mid-13c. (late 12c. as a surname), attested from late 14c. in the sense of "one who uses offensive or impious language, one who jests irreverently."
This is from Old French ribaut, ribalt "rogue, scoundrel, lewd lover," also as an adjective, "wanton, depraved, dissolute, licentious," a word of uncertain origin, perhaps (with suffix -ald) from riber "be wanton, sleep around, dally amorously," from a Germanic source (compare Old High German riban "be wanton," literally "to rub," possibly from the common euphemistic use of "rub" words in venery, from Proto-Germanic *wribanan from PIE root *wer- (2) "to turn, bend").
Other early adjectival forms were ribaldous "riotous, unruly" (c. 1400); ribaldy (early 15c.).