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.
"wolf-like," 1650s, from French lupin "wolf-like; vicious, ferocious," from Latin lupinus "of the wolf" (source also of Spanish and Italian lupino), from lupus "wolf" (see wolf (n.)).
"cruel," late 13c., possibly late Old English, perhaps from Old French fel "cruel, fierce, vicious," from Medieval Latin fello "villain" (see felon). Phrase at one fell swoop is from "Macbeth." Related: Fellness.
"to render vicious, faulty, or imperfect; injure the quality or substance of," 1530s, from Latin vitiatus, past participle of vitiare "to make faulty, injure, spoil, corrupt," from vitium "fault, defect, blemish, crime, vice" (see vice (n.1)). Related: Vitiated; vitiating.
"debauchee, libertine; idle, dissolute person; one who goes about in search of vicious pleasure," 1650s, shortening of rakehell. Hogarth's "Rake's Progress" engravings were published in 1735. Generally of men but also used by 1712 of women of similar character.
"thing of little value," 1815, earlier "inferior or worn-out horse" (1778, though OED regards this earlier appearance as "prob. accidental"), a word of uncertain origin, perhaps altered from slang rep "man of loose character; vicious, reckless and worthless person" (1747), which itself is of obscure origin, perhaps short for reprobate (n.). But also compare demi-rep "woman of dubious virtue" (1749, the second element said to be short for reputation).
"habitually lewd or profligate person, one addicted to vicious indulgence in sensual pleasures," 1660s, from French débauché "debauched (person)," noun use of past participle of debaucher (see debauch).
Debauchee, n. One who has so earnestly pursued pleasure that he has had the misfortune to overtake it. [Ambrose Bierce, "Devil's Dictionary," 1911]