satan

Short definition from Wiktionary

Noun

1. 1
   Alternative form of Satan (especially in the sense "a demon follower of Satan; a fallen angel").
2. 2
   Obsolete form of satin.
3. 3
   A demon follower of Satan (principal evil spirit); a fallen angel.
4. 4
   Anything that causes destruction or is viewed as evil.

Proper noun

1. 1
   The supreme evil spirit in the Abrahamic religions, who tempts humanity into sin; the Devil; (Theistic Satanism) the same figure, regarded as a deity to be revered and worshipped.
2. 2
   A person or animal regarded as particularly malignant, detestable, or evil; used as an epithet or as a name for an animal.