1(c.1005-1057) the king of Scotland from 1040 to 1057, who killed the previous king, Duncan, in battle and was himself later killed by Duncan's son, Malcolm
2a character in the play Macbeth by William Shakespeare. Macbeth is told by three witches that he will become king. To do so, he murders the present king Duncan, who is visiting him in his castle. Although he feels very guilty about this, he kills several other people to keep his power until he is finally killed byMacduff.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.