antagonista person who opposes another, often in a hostile manner: The man was his antagonist in a duel.; an enemy, foe; the adversary of the hero or protagonist in a literary workNot to be confused with:adversary ? a person, group, or force that opposes or attacks; opponent; enemy; foe; one who is an opponent in a contest; a contestant; one who fights determinedly and relentlessly: He was a worthy adversary.adversity ? catastrophe, disaster; trouble, misery; adverse fortune or fate; a condition marked by misfortune: In times of adversity, she crumbles.Abused, Confused, & Misused Words by Mary Embree Copyright © 2007, 2013 by Mary Embreean·tag·o·nist (?n-t?g??-n?st)n.1. One who opposes and contends against another; an adversary.2. The principal character in opposition to the protagonist or hero of a narrative or drama.3. Physiology A muscle that counteracts the action of another muscle, the agonist.4. A drug or chemical substance that interferes with the physiological action of another, especially by combining with and blocking its receptor.an·tag?o·nis?tic adj.an·tag?o·nis?ti·cal·ly adv.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.antagonist (æn?tæ??n?st) n1. an opponent or adversary, as in a contest, drama, sporting event, etc2. (Physiology) any muscle that opposes the action of another. Compare agonist13. (Pharmacology) a drug that counteracts the effects of another drug. Compare synergist1Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014an?tag?o?nist (æn?tæg ? n?st) n. 1. a person who is opposed to or competes with another; opponent; adversary. 2. (in drama or literature) the opponent of the hero or protagonist. 3. a muscle that acts in opposition to another. Compare agonist (def. 3). 4. a tooth in one jaw that articulates with a tooth in the other jaw. 5. a drug that counteracts the effects of another drug. [1590?1600;