apprehensive, a. discerning, apt; fearful, anxious, worried.

approachable, a. accessible. Antonym: unapproachable.

appropriate, a. fitting, proper, applicable, apposite, pertinent,
fit. Antonyms: See inappropriate.

approval, n. approbation, sanction, commendation, liking,
indorsement. Antonyms: See disapproval.

approve, v. commend, sanction, countenance, favor, like.

apron, n. pinafore, tier; boot.

apt, a. fit, relevant, appropriate, germane, applicable, felicitous,
pertinent, _apropos_; likely, liable; clever, intelligent, bright, deft.
Antonyms: See inapt.

aptitude, n. proneness, propensity, leaning, proclivity, inclination.
Antonym: inaptitude.

aptness, n. appropriateness, pertinence; intelligence, cleverness.

arbitrary, a. tyrannical, absolute, imperious, unrestrained,
dictatorial.

arbitrator, n. arbiter, umpire, judge, referee.

arbor, n. bower, pergola, trellis.