A priori, [L.] Theoretically, before experience, before trial, from assumed principles.

Apropos, a. [Fr.] Opportune, seasonable, timely, fit, suitable, apt, apposite, to the point, to the purpose, just the thing, quite the thing.

Apropos, ad. Opportunely, seasonably, to the purpose.

Apt, a. 1. Apposite, pertinent, suitable, fit, fitting, meet, befitting, germane, applicable, appropriate, apropos, to the point, to the purpose.

2. Inclined, liable, prone, disposed.

3. Quick, sharp, ready, prompt, expert, dexterous, able, clever, happy, adroit, handy, skilful.

4. Docile, teachable.

Aptitude, n. Turn, disposition, genius, gift, endowment, talent, faculty, capacity, capableness, tendency, inclination, bias, proclivity, proneness, propensity, forte, aptness.

Aptness, n. 1. Fitness, suitableness, appropriateness, adaptation, applicability.

2. Turn, tendency, inclination, aptitude.

3. Quickness, readiness, expertness, skill, facility, knack, adroitness, address, ability.

4. Docility, teachableness.

Aqua-fortis, n. [L.] Nitric acid (somewhat diluted), spirit of nitre.

Aqua-regia, n. [L.] Nitro-muriatic acid, nitro-chloro-hydric acid.

Aquarius, n. (Astron.) Water-bearer.

Aqueous, a. Watery, waterish, moist, wet, humid, damp.

Aquiline, a. Hooked (like an eagle's beak; applied especially to the nose), bent, curved.

Arab, n. Arabian, Saracen.

Arabesque, a. Moorish, moresque.

Arabian, a. Arabic.

Arabian, n. Arab, Saracen.

Arabic, a. Arabian.

Arable, a. That may be ploughed, fit for the plough, suitable for cultivation.

Arbiter, n. Arbitrator, umpire, judge, referee.

Arbitrament, n. 1. Choice, option, will, determination, decision, umpirage.

2. (Law.) Award, adjudication, determination, decision, decree.

Arbitrariness, n. Despotism, absoluteness, absolutism, tyranny, autocracy.

Arbitrary, a. 1. Irresponsible, absolute, tyrannical, tyrannous, imperious, domineering, bound by no law.

2. Optional, voluntary, determined by no rule or principle.

Arbitrate, v. a. Decide, determine.

Arbitrate, v. n. 1. Mediate, intercede, interpose.

2. Judge, decide, determine, adjudicate, give judgment, pass judgment.

Arbitration, n. 1. Mediation, intervention, intercession, interposition.

2. Decision, determination, adjudication, arbitrament, umpirage.

Arbitrator, n. Arbiter, umpire, judge, referee.

Arbor, n. 1. Bower, shady recess, shady retreat.

2. Spindle, axis, shaft.

Arborescence, n. Branching, ramification.

Arborescent, a. Dendriform, dendrite, dendritic, arboriform, branching.

Arboriform, a. Dendriform, arborescent.

Arbor-vitae, n. White cedar (of Canada; Thuja occidentalis).

Arc, n. (Geom.) Arch, part of a circumference.

Arcade, n. Piazza, colonnade.

Arcanum, n. [L. pl. Arcana.] Secret, mystery.

Arch, n. 1. (Geom.) Arc, part of a circumference.

2. Curved structure.

Arch, v. a. 1. Vault, cover with an arch, arch over.

2. Bend into the form of an arch.

Arch, a. 1. Chief, principal, consummate, first-rate, of the first class.

2. Sly, shrewd, cunning, wily, astute, subtle.

3. Roguish, waggish, mirthful, frolicsome, sportive, merry, playful.

Archaeologian, n. Archaeologist.

Archaeological, a. Antiquarian.

Archaeologist, n. Antiquarian, antiquary.

Archaeology, n. Science of antiquities.

Archaic, a. Old, ancient, obsolete, antiquated, antique, by-gone, out of use, out of date, out of fashion, old-fashioned.

Archaism, n. Antiquated term or expression.

Archbishop, n. Primate, metropolitan.

Archduchy, n. Archdukedom.

Archdukedom, n. Archduchy.

Arched, a. 1. Vaulted, bowed, camerated, concave.

2. (Bot.) Fornicate.

Arched-ceiling, n. [L.] Vault.

Arched roof, n. [L.] Vault.

Arch-enemy, n. Arch-fiend.

Arch-fiend, n. Devil, Satan.

Archer, n. Bowman, sagittary.

Arch over, Arch, cover with an arch.

Archetype, n. Pattern, model, type, prototype, original, examplar, example, protoplast, mirror, paragon.