The Collaborative International Dictionary of English v.0.48:

Trump \Trump\, v. i. [imp. & p. p. Trumped; p. pr. & vb. n.
   Trumping.]
   To play a trump card when one of another suit has been led.
   [1913 Webster]

WordNet (r) 3.0 (2006):

trumping
    n 1: (card games) the act of taking a trick with a trump when
         unable to follow suit [syn: ruff, trumping]