singleton has definitions from the fields of cards,mathematics
1
[ noun ] a set containing a single member

Related terms

set

2
[ noun ] (mathematics) a single object (as distinguished from a pair)

Related terms

one

3
[ noun ] Last name, frequency rank in the U.S. is 484
4
[ noun ] (cards) the playing card that is the only card in a suit held in a bridge hand as initially dealt

Related terms

playing_card

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