- a person who is opposed to, struggles against, or competes with another; opponent; adversary.
- the adversary of the hero or protagonist of a drama or other literary work: Iago is the antagonist of Othello.
- a muscle that acts in opposition to another.
- a tooth in one jaw that articulates during mastication or occlusion with a tooth in the opposing jaw.
- a drug that counteracts the effects of another drug.
- an opponent or adversary, as in a contest, drama, sporting event, etc
- any muscle that opposes the action of another
- a drug that counteracts the effects of another drug
