(noun)
in informal usage, a person who is excellent at some activity, especially a very strong player in some sport;
e.g. The baseball ace was inducted into the sport's hall of fame.
(noun)
a combat (air force) pilot who has successfully shot down many enemy aircrafts;
e.g. The commander appointed his best ace to fly the plane.
(verb)
to gain a significant advantage over someone and then overcome or defeat them in some competition (usually used as "ace out");
e.g. They were able to ace out their rivals and become the most popular brand of the product.
(verb)
in American usage, to excel at something and perform extremely well at it, especially to score high marks (or a high grade) on an exam or test;
e.g. She is confident that she will ace the final exam.
(adjective)
of very high quality or rank, especially of the first rank or quality;
e.g. He is a famous ace detective.
(adjective)
not feeling sexual attraction or desire, i.e. asexual;
e.g. The incident made her realize that she was asexual.
(noun)
a single shot that wins a point in some sport, such as a serve that one's opponent fails to return in games like tennis or a single stroke that scores a hole in golf;
e.g. The tennis player served an ace that earned him the winning point of the game.
(noun)
a person who does not experience sexual attraction or desire, i.e. a person who is asexual;
e.g. He is the only ace I know who feels that way.
(verb)
to score a point against an opponent with a single shot, for example to deliver a service that one's opponent cannot return (in games like tennis) or to only take a single stroke to score a hole in golf;
e.g. She can ace her opponents by spinning the ball when she serves.