at

atone (v.) to repent, make amends (The man atoned for forgetting his wife’s birthday by buying her five dozen roses.)

atrophy (v.) to wither away, decay (If muscles do not receive enough blood, they will soon atrophy and die.)

attain (v.) to achieve, arrive at (The athletes strived to attain their best times in competition.)

attribute 1. (v.) to credit, assign (He attributes all of his success to his mother’s undying encouragement.) 2. (n.) a facet or trait (Among the beetle’s most peculiar attributes is its thorny protruding eyes.)

atypical (adj.) not typical, unusual (Screaming and crying is atypical adult behavior.)