D defs.my
Entry 1 sense Webster, 1913

Singleton

/sĭng'-gəl-tən/ · Sin·gle·ton · IPA /ˈsɪŋ.ɡ(ə)l.tən/
01 n. In certain games at cards, as whist, a single card of any suit held at the deal by a player; as, to lead a singleton.
  1. 1.
    In certain games at cards, as whist, a single card of any suit held at the deal by a player; as, to lead a singleton.