noun

1. a playing card, domino, etc. marked with one large, centered pip
2. Racket Sports, Handball
   1. a score made by a serve that one's opponent fails to touch
   2. such a serve
3. Golf the act of hitting the ball so that it goes into the hole on the drive; hole in one
4. a combat pilot who has destroyed at least five enemy planes
5. an expert in any activity

Etymology: ME as, aas < L as, unit, unity, as

adjective

transitive verb aced, acing ac′·ing

1. to score an ace against, as in tennis
2. to make an ace on (a particular hole) in golf
3. Slang to defeat completely; get the best of: often with out
4. ☆ Informal to do very well, esp., by earning a grade of A, in, on, etc. she aced the course