Meaning of ACE in English

I. ace 1 /eɪs/ BrE AmE noun [countable]

[ Date: 1300-1400 ; Language: Old French ; Origin: as , from Latin , 'unit, a small coin' ]

1 . PLAYING CARD a playing card with a single spot on it, which usually has the highest value in a game:

the ace of hearts

I’ve got a pair of aces.

2 . SKILFUL PERSON someone who is extremely skilful at doing something:

a soccer ace

cycling ace Chris Boardman

3 . TENNIS SHOT a first shot in tennis or ↑ volleyball which is hit so well that your opponent cannot reach the ball and you win the point

4 . hold the aces to have the advantages in a situation so that you are sure to win:

The Americans hold most of the aces in this technology.

5 . within an ace of (doing) something very close to doing or achieving something:

The team came within an ace of winning the championship.

6 . have an ace up your sleeve to have a secret advantage which could help you to win or be successful

7 . ace in the hole American English informal something that you keep secretly to use when you need it:

That fifty dollars is my ace in the hole.

II. ace 2 BrE AmE adjective

1 . ace pilot/player/skier etc someone who is a very skilful pilot, player etc:

an ace marksman

2 . British English spoken very good:

The party was ace.

III. ace 3 BrE AmE verb [transitive]

1 . American English informal to do very well in an examination, a piece of written work etc:

I aced the History test.

2 . to hit your first shot in tennis or ↑ volleyball so well that your opponent cannot reach the ball

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.