villainous

adj. wicked, sinful; loathsome, abhorrent

A villain is an "evil" character in a story, whether an historical narrative or, especially, a work of fiction. The villain is the bad guy, the characters who fight against the hero. A female villain is sometimes called a villainess.A villain's disposition towards evil distinguishes them from an antagonist. For example, Javert in Les Miserables is an antagonist: He opposes the hero, but does so by such means and under such pretexts as not to become entirely odious to the reader; a villain may, in fact, even repent, be redeemed, or become a "good guy" in the end. (A villain is virtually always an antagonist, but an antagonist is not always a villain.) The villain is also distinct from the anti-hero, a character who violates the law or the prevailing social standards, but who nevertheless has the audience's sympathy (and may be or become good-hearted), and is therefore the real hero of the story. Sometimes, a villain may even appear as the protagonist of a story, while the hero who opposes them may be the antagonist.
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Adjective
1. extremely wicked; "nefarious schemes"; "a villainous plot"; "a villainous band of thieves"
(synonym) nefarious
(similar) wicked

(a.)
Sorry; mean; mischievous; -- in a familiar sense.
  

(a.)
Proceeding from, or showing, extreme depravity; suited to a villain; as, a villainous action.
  

(a.)
Base; vile; mean; depraved; as, a villainous person or wretch.
  

Synonyms and related words:
abandoned, abominable, arrant, atrocious, awful, bad, base, beastly, beneath contempt, bent, black, blackguardly, blamable, blameworthy, brutal, contemptible, contrary, corrupt, criminal, crooked, damnable, dark, debased, degenerate, degraded, deplorable, despicable, detestable, dire, disgraceful, disgusting, dishonest, dissolute, dreadful, egregious, enormous, evil, execrable, faithless, felonious, fetid, filthy, flagitious, flagrant, foul, fulsome, grievous, gross, hateful, heinous, horrible, horrid, improper, infamous, iniquitous, knavish, lamentable, loathsome, lousy, low, miscreant, monstrous, murderous, nasty, naughty, nefarious, noisome, notorious, objectionable, obnoxious, odious, offensive, outrageous, peccant, perfidious, perverse, perverted, pitiable, pitiful, profligate, putrid, rank, rascally, recreant, regrettable, reprehensible, reprobate, repulsive, roguish, rotten, sad, scampish, scandalous, schlock, scoundrelly, scurvy, shabby, shameful, shocking, shoddy, sinful, sordid, squalid, terrible, too bad, traitorous, treacherous, unclean, unforgivable, unpardonable, unscrupulous, unspeakable, unworthy, vicious, vile, wicked, woeful, worst, worthless, wretched, wrong