Villein (pronounced "vill-ain") was the term used in the feudal era to denote a peasant (tenant farmer) who was legally tied to the land he worked on. An alternative term is serf (from Latin servus = "slave"). A villein could not leave the land without the landowner's consent. Villeins thus occupied the social space between a free peasant (or "freeman") and a slave. The majority of medieval European peasants were villeins. Basically, they are villagers.
The term derives from Late Latin villanus, meaning a man employed at a Roman villa rustica, or large agricultural estate. The system of tied serfdom originates from a decree issued by the late Roman Emperor Diocletian (ruled 284-305) in an attempt to prevent the flight of peasants from the land and the consequent decline in food production. The decree obliged peasants to register in their locality and never leave it.
Because of the low status, the term became derogatory. In modern French vilain means "ugly" or "naughty" and in Italian, villano means "rude" or "ill-mannered". In modern English villain means a scoundrel or criminal.
<EXAMPLE> ORLANDO I am no villain; I am the youngest son of Sir Rowland de Boys; he was my father, and he is thrice a villain that says such a father begot villains. Wert thou not my brother, I would not take this hand from thy throat till this other had pulled out thy tongue for saying so: thou hast railed on thyself.(Source:As You Like It Act 1 Scene 1 lines 55 to 61) ]