DEUCE, a term applied to the "two" of any suit of cards, or of dice. It is also a term in tennis when both sides have each scored three points in a game, or five games in a set; to win the game or set two points or games must then be won consecu tively, and the players return to a position of equality as often as they cannot score two such points or games consecutively. The earliest instances in English of the use of the slang expression "the deuce," in exclamations, date from the middle of the 17th century.