antagonist

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antagonist

1. any muscle that opposes the action of another
2. a drug that counteracts the effects of another drug

antagonist

[an′tag·ə‚nist]
(biochemistry)
A molecule that bears sufficient structural similarity to a second molecule to compete with that molecule for binding sites on a third molecule.
(pharmacology)
A drug or other chemical substance capable of reducing the physiological activity of another chemical substance; refers especially to a drug that opposes the action of a drug or other chemical substance on the nervous system by combining with and blocking the nerve receptor.
(physiology)
A muscle that contracts with, and limits the action of, another muscle, called an agonist, with which it is paired.
References in classic literature ?
As he fell he saw a black streak shoot above him and another lion close upon his antagonist. Rolling from beneath the two battling lions Tarzan regained his feet, though he was half dazed and staggering from the impact of the terrible blow he had received.
With the eyes of an immense concourse of spectators fixed upon them, the five knights advanced up the platform upon which the tents of the challengers stood, and there separating themselves, each touched slightly, and with the reverse of his lance, the shield of the antagonist to whom he wished to oppose himself.
The antagonist of Grantmesnil, instead of bearing his lance-point fair against the crest or the shield of his enemy, swerved so much from the direct line as to break the weapon athwart the person of his opponent a circumstance which was accounted more disgraceful than that of being actually unhorsed; because the latter might happen from accident, whereas the former evinced awkwardness and want of management of the weapon and of the horse.
The wings of these flyers had bat-like hooks forward, by which they were to cling to their antagonist's gas-chambers while boarding him.
In all previous forms of war, both by land and sea, the losing side was speedily unable to raid its antagonist's territory and the communications.
So it was that though Sing passed within a few paces of the unconscious man he neither saw nor heard aught of him or his antagonists.
Both Number Twelve and Number Three had assured him that the beasts had not recaptured her, for they had seen the entire band flee madly through the jungle after hearing the report of the single shot which had so terrorized Bulan's antagonists. Bulan did not know what to make of this occurrence which he had not himself heard, the shot having come after he had lost consciousness at the foot of the tree; but from the description of the noise given him by Number Twelve he felt sure that it must have been the report of a gun, and hoped that it betokened the presence of Virginia Maxon's friends, and that she was now safe in their keeping.
But as we strained and struggled about the tree into which Tars Tarkas was clambering with infinite difficulty, I suddenly caught a glimpse over the shoulder of my antagonist of the great swarm of pursuers that now were fairly upon me.
But they were silent in amazement and expectation when they saw the mighty white ape wriggle upon the back of their king, and, with steel muscles tensed beneath the armpits of his antagonist, bear down mightily with his open palms upon the back of the thick bullneck, so that the king ape could but shriek in agony and flounder helplessly about upon the thick mat of jungle grass.
As the brute circled him Tarzan turned slowly, keeping his eyes ever upon the eyes of his antagonist. He had appraised the young bull as one who had never quite felt equal to the task of overthrowing his former king, but who one day would have done so.
Had Tarzan been a full-grown bull ape of the species of his tribe he would have been more than a match for the gorilla, but being only a little English boy, though enormously muscular for such, he stood no chance against his cruel antagonist. In his veins, though, flowed the blood of the best of a race of mighty fighters, and back of this was the training of his short lifetime among the fierce brutes of the jungle.
Kala could not understand, for the voice of Bolgani had at last been raised in the agony of suffering and death, but no sound had come to her by which she possibly could determine the nature of his antagonist.