What is "to bate an ace"

Ace \Ace\ ([=a]s), n.; pl. Aces ([=a]"s[e^]z). [OE. as, F. as, fr. L. as, assis, unity, copper coin, the unit of coinage. Cf. As.]

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.

3. (Sport) A single point won by a stroke, as in handball, rackets, etc.; in tennis, frequently, a point won by a service stroke.

   To bate an ace, to make the least abatement. [Obs.]

   Within an ace of, very near; on the point of.
   --W. Irving.