1.  antagonism(n = noun.state) enmity, hostility - a state of deep-seated ill-will;
is a kind of state
has particulars: latent hostility, tension, state of war, war, cold war, suspicion, cold war
Derived forms verb antagonise₂, noun antagonist₁, adjective antagonistic₅, adjective antagonistic₂, verb antagonize₁

2.  antagonism(n = noun.linkdef) - the relation between opposing principles or forces or factors; "the inherent antagonism of capitalism and socialism"
is a kind of oppositeness, opposition
Derived forms verb antagonise₁, noun antagonist₁, adjective antagonistic₂, adjective antagonistic₁

3.  antagonism(n = noun.feeling) - an actively expressed feeling of dislike and hostility;
is a kind of dislike, enmity, hostility, ill will
Derived forms verb antagonise₂, noun antagonist₁, adjective antagonistic₃, verb antagonize₁

4.  antagonism(n = noun.act) - (biochemistry) interference in or inhibition of the physiological action of a chemical substance by another having a similar structure;
is a kind of hinderance, hindrance, interference
Derived forms noun antagonist₃, adjective antagonistic₄

   Opposition of action; counteraction or contrariety of things or principles. [1913 Webster]
" We speak of antagonism between two things, to or against a thing, and sometimes with a thing." [1913 Webster]

antagonism, n. active opposition or hostility.

Etymology:
F antagonisme (as ANTAGONIST)

N  contrariety, contrast, foil, antithesis, oppositeness, contradiction, antagonism, clashing, repugnance, inversion, the opposite, the reverse, the inverse, the converse, the antipodes, the antithesis, the other extreme, contrary, contrarious, contrariant, opposite, counter, dead against, converse, reverse, opposed, antithetical, contrasted, antipodean, antagonistic, opposing, conflicting, inconsistent, contradictory, at cross purposes, negative, hostile, differing toto coelo, diametrically opposite, diametrically opposed, as opposite as black and white, as opposite as light and darkness, as opposite as fire and water, as opposite as the poles, as different as night and day, Hyperion to a satyr, quite the contrary, quite the reverse, no such thing, just the other way, tout au contraire, contrarily, contra, contrariwise, per contra, on the contrary, nay rather, vice versa, on the other hand, all concord's born of contraries, Thesis, antithesis, synthesis.

N  opposition, antagonism, oppugnancy, oppugnation, impugnation, contrariety, contravention, counteraction, counterplot, cross fire, undercurrent, head wind, clashing, collision, conflict, competition, two of a trade, rivalry, emulation, race, absence of aid, resistance, restraint, hindrance, opposing, opposed, adverse, antagonistic, contrary, at variance, at issue, at war with, unfavorable, unfriendly, hostile, inimical, cross, unpropitious, in hostile array, front to front, with crossed bayonets, at daggers drawn, up in arms, resistant, competitive, emulous, against, versus, counter to, in conflict with, at cross purposes, against the grain, against the current, against the stream, against the wind, against the tide, with a headwind, with the wind ahead, with the wind in one's teeth, in spite, in despite, in defiance, in the way, in the teeth of, in the face of, across, athwart, overthwart, where the shoe pinches, in spite of one's teeth, though, even, quand meme, per contra, nitor in adversum.

N  counteraction, opposition, contrariety, antagonism, polarity, clashing, collision, interference, inhibition, resistance, renitency, friction, reaction, retroaction, counterblast, neutralization, vis inertiae, check, voluntary opposition &c, voluntary resistance, repression, opposites, action and reaction, yang and yin, yang-yin (contrariety), counteracting, antagonistic, conflicting, retroactive, renitent, reactionary, contrary, although, in spite of, against, for every action there is a reaction, equal in force and opposite in direction.