villain

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A wicked or evil person; a scoundrel.
2. n. A dramatic or fictional character who is typically at odds with the hero.
3. n. Variant of villein.
4. n. Something said to be the cause of particular trouble or an evil: poverty, the villain in the increase of crime.
5. n. Obsolete A peasant regarded as vile and brutish.

Century Dictionary and Cyclopedia

1. n. A member of the lowest class of unfree persons during the prevalence of the feudal system; a feudal serf. In respect to their lords or owners the villains had no rights, except that the lord might not kill or maim them, or ravish the females; they could acquire or hold no property against their lord's will; they were obliged to perform all the menial services he demanded; and the cottages and plots of land they occupied were held merely at his will. In respect, however, of other persons besides their lord they had the rights and privileges of freemen. Villains were either regardant (which see) or in gross. They were in view of the law annexed to the soil (adscripti or adscriptitii glebæ), belonging to a manor as fixtures, passing with it when it was conveyed or inherited, and they could not be sold or transferred as persons separate from the land. The latter belonged personally to their lord, who could sell or transfer them at will.
2. n. Hence An ignoble or base-born person generally; a boor, peasant, or clown.
3. n. A man of ignoble or base character; especially, one who is guilty or capable of gross wickedness; a scoundrel; a knave; a rascal; a rogue: often used humorously in affectionate or jocose reproach.
4. Of or pertaining to, or consisting of, villains or serfs.
5. Characteristic of or befitting a villain or slave; servile; base; villainous.
6. To debase; degrade; villainize.

Wiktionary

1. n. this sense?) (The addition of quotations indicative of this usage is being sought): A vile, wicked person.
2. n. An extremely depraved person, or one capable or guilty of great crimes.
3. n. A deliberate scoundrel.
4. n. The bad person in a work of fiction; often the main antagonist of the hero.
5. n. A villain was in a low level of medieval serfdom. A cotter may have been lower.

GNU Webster's 1913

1. n. One who holds lands by a base, or servile, tenure, or in villenage; a feudal tenant of the lowest class, a bondman or servant.
2. n. A baseborn or clownish person; a boor.
3. n. A vile, wicked person; a man extremely depraved, and capable or guilty of great crimes; a deliberate scoundrel; a knave; a rascal; a scamp.
4. adj. Villainous.
5. v. To debase; to degrade.

WordNet 3.0

1. n. the principal bad character in a film or work of fiction
2. n. a wicked or evil person; someone who does evil deliberately