doubleton (plural doubletons)
- (mathematics, rare) A set containing precisely two elements.
- (bridge) A pair of cards of the same suit, which are the only cards of that suit in a player's hand
–2009, January 8, “Phillip Alder”[New York Times], Part 1 of an Experiment, Ending in a Trump Coup:
- If she had had the doubleton ace of diamonds and a low club, she would have made a four-club splinter bid, showing four-card spade support, the values for game and a singleton or void in clubs.