Antagonist

Part of speech: noun (n.)

1. One who contends with another, especially in combat; an adversary; an opponent. Antagonist of Heaven's Almigthy King. Milton. Our antagonists in these controversies. Hooker.

2. A muscle which acts in opposition to another; as a flexor, which bends a part, is the antagonist of an extensor, which extends it.

3. A medicine which opposes the action of another medicine or of a poison when absorbed into the blood or tissues.

Synonyms: Adversary; enemy; opponent; toe; competitor. See Adversary.

Part of speech: adjective (a.)

Antagonistic; opposing; counteracting; as, antagonist schools of philosophy.