Aptitude. Disposition, knack, endowment, tendency, inclination, fitness, suitability, bias, propensity.
Ant. Unreadiness, unskilfulness, repugnance, incongruity.
Arbiter. Umpire, judge, referee; controller, master, lord.
Ant. Appellant, claimant, litigant, disputant.
Arbitrary. Despotic, autocratic, tyrannical, overbearing, peremptory; capricious, wilful, fanciful; imperious, dictatorial.
Ant. Considerate, lenient, obliging, equitable.
Arbitration. Mediation, intercession, interposition, intervention; arbitrament, umpirage, trial, judgment, decision.
Ant. Litigation, contention, disputation, appeal, dissension.
Ardent. Passionate, fervent, intense, vehement, fierce, fiery; hot, burning; zealous, enthusiastic, strenuous.
Ant. Cool, cold, indifferent, torpid, apathetic, dispassionate, phlegmatic.