adversary, adversative, adverse, alien, antagonist, antagonistic, anti, antipathetic, antithetic, assailant, clashing, combatant, competitive, competitor, con, conflicting, contender, contestant, contradictory, contrary, counter, counteragent, cross, disaccordant, disputant, dissentient, enemy, foe, fractious, hostile, inimical, match, negative, noncooperative, obstinate, opposed, opposer, opposing, opposite, oppositional, oppositive, oppugnant, overthwart, perverse, recalcitrant, refractory, repugnant, rival, the opposition, uncooperative, unfavorable, unfriendly, unpropitious