What does the word ace mean?

Usage examples for ace

  1. The King is the Cornish army, yonder: the Ace is my pistol here, which I hold. – The Splendid Spur by Arthur T. Quiller Couch
  2. " I pay King and Ace only," he called out imperturbably, as he turned up a Queen. – The Nest of the Sparrowhawk by Baroness Orczy