noun, verb, aced, ac⋅ing, adjective | 1. | a playing card or die marked with or having the value indicated by a single spot: He dealt me four aces in the first hand. |
| 2. | a single spot or mark on a playing card or die. |
| 3. | (in tennis, badminton, handball, etc.)
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| 4. | a fighter pilot credited with destroying a prescribed number or more of enemy aircraft, usually five, in combat. |
| 5. | a very skilled person; expert; adept: an ace at tap dancing. |
| 6. | Slang. a one-dollar bill. |
| 7. | Slang. a close friend. |
| 8. | Golf.
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| 9. | Slang. a barbiturate or amphetamine capsule or pill. |
| 10. | a very small quantity, amount, or degree; a particle: not worth an ace. |
| 11. | Slang. a grade of A; the highest grade or score. |
| 12. | (in tennis, badminton, handball, etc.) to win a point against (one's opponent) by an ace. |
| 13. | Golf. to make an ace on (a hole). |
| 14. | Slang. to cheat, defraud, or take advantage of (often fol. by out): to be aced out of one's inheritance; a friend who aced me out of a good job. |
| 15. | Slang.
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| 16. | excellent; first-rate; outstanding. |
| 17. | ace it, Slang. to accomplish something with complete success: a champion who could ace it every time. |
| 18. | ace up one's sleeve, an important, effective, or decisive argument, resource, or advantage kept in reserve until needed. |
| 19. | be aces with, Slang. to be highly regarded by: The boss says you're aces with him. |
| 20. | easy aces, Auction Bridge. aces equally divided between opponents. |
| 21. | within an ace of, within a narrow margin of; close to: He came within an ace of winning. |

within an ace of
Also, within an inch of. Very close to, within a narrow margin of, as in We were within an ace of calling you, but we'd lost your phone number, or We were within an inch of buying tickets for that concert. The first term refers to the ace of dice, that is, the one pip on a die. The lowest number one can throw with a pair of dice is two (two aces), a throw that is within an ace of one. The term began to be used for other kinds of near miss by about 1700.