Longman Dictionary of Contemporary English - ace

~1 n 1 a playing card with a single spot on it, which usually has the highest value in a game  (the ace of hearts) 2 have an ~ up your sleeve to have a secret advantage which could help you to win or be successful 3 hold all the ~s to have all the advantages in a situation so that you are sure to win 4 be/come within an ~ of to very nearly succeed in doing something  (She came within an ace of getting the job as Export Manager.) 5 a first shot in tennis or volleyball which is hit so well that your opponent cannot reach the ball and you win the point 6 someone who is extremely skilful at doing something  (a World War II flying ace | an ace at chess) 7 ~ in the hole AmE informal something that you keep secretly to use when you need it  (That fifty dollars is my ace in the hole.) ~2 adj 1 ~ pilot/player/skier etc someone who is a very skilful pilot, player etc  (ace footballer Diego Maradona) 2 BrE slang very good  (The party was ace.) ~3 v 1 AmE informal to do very well in an examination, a piece of written work etc  (I think I aced the History test.) 2 to hit your first shot in tennis or volleyball so well that your opponent cannot reach the ball