1 A unit; a single point or spot on a card or die; the card or die so marked; as, the ace of diamonds.
2 Hence: A very small quantity or degree; a particle; an atom; a jot. I ‘ll not wag an ace further. Dryden. To bate an ace, to make the least abatement. [Obs.] — Within an ace of, very near; on the point of. W. Irving.