brave (adj.)youdaoicibaDictYouDict[brave 词源字典]
late 15c., from Middle French brave, "splendid, valiant," from Italian bravo "brave, bold," originally "wild, savage," possibly from Medieval Latin bravus "cutthroat, villain," from Latin pravus "crooked, depraved;" a less likely etymology being from Latin barbarus (see barbarous). A Celtic origin (Irish breagh, Cornish bray) also has been suggested.

Old English words for this, some with overtones of "rashness," included modig (now "moody"), beald ("bold"), cene ("keen"), dyrstig ("daring"). Brave new world is from the title of Aldous Huxley's 1932 satirical utopian novel; he lifted the phrase from Shakespeare ("Tempest" v.i.183).[brave etymology, brave origin, 英语词源]
deprave (v.)youdaoicibaDictYouDict
late 14c., "corrupt, lead astray, pervert," from Old French depraver (14c.) or directly from Latin depravare "distort, disfigure;" figuratively "to pervert, seduce, corrupt," from de- "completely" (see de-) + pravus "crooked." Related: Depraved; depraving.
forlorn (adj.)youdaoicibaDictYouDict
mid-12c., forloren "disgraced, depraved," past participle of obsolete forlesan "be deprived of, lose, abandon," from Old English forleosan "to lose, abandon, let go; destroy, ruin," from for- "completely" + leosan "to lose" (see lose). In the Mercian hymns, Latin perditionis is glossed by Old English forlorenisse. OED's examples of forlese end in 17c., but the past participle persisted. Sense of "forsaken, abandoned" is 1530s; that of "wretched, miserable" first recorded 1580s.

A common Germanic compound (cognates: Old Saxon farilosan, Old Frisian urliasa, Middle Dutch verliesen, Dutch verliezen, Old High German virliosan, German verlieren, Gothic fraliusan "to lose").

In English now often in forlorn hope (1570s), which is a partial translation of Dutch verloren hoop, in which hoop means "troop, band," literally "heap," and the sense of the whole phrase is of a suicide mission. The phrase more often than not is used in English as if it meant "a faint hope, and the misuse has colored the meaning of forlorn. Related: Forlornly; forlornness.
ribald (adj.)youdaoicibaDictYouDict
c. 1500, from ribald, ribaud (n.), mid-13c., "a rogue, ruffian, rascall, scoundrell, varlet, filthie fellow" [Cotgrave], from Old French ribaut, ribalt "rogue, scoundrel, lewd lover," also as an adjective, "wanton, depraved, dissolute, licentious," 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 to mean "have sex"), from Proto-Germanic *wribanan, from PIE root *wer- (3) "to turn, bend" (see versus).
vicious (adj.)youdaoicibaDictYouDict
late 14c., "unwholesome, impure, of the nature of vice, wicked, corrupting, pernicious, harmful;" of a text, "erroneous, corrupt," from Anglo-French vicious, Old French vicios "wicked, cunning, underhand; defective, illegal" (Modern French vicieux), from Latin vitiosus (Medieval Latin vicious) "faulty, full of faults, defective, corrupt; wicked, depraved," from vitium "fault" (see vice (n.1)).

Meaning "inclined to be savage or dangerous" is first recorded 1711 (originally of animals, especially horses); that of "full of spite, bitter, severe" is from 1825. In law, "marred by some inherent fault" (late 14c.), hence also this sense in logic (c. 1600), as in vicious circle in reasoning (c. 1792, Latin circulus vitiosus), which was given a general sense of "a situation in which action and reaction intensify one another" by 1839. Related: Viciously (mid-14c., "sinfully"); viciousness.