The Collaborative International Dictionary of English v.0.48:
Frivol \Friv"ol\, v. i. To act frivolously; to trifle. --Kipling. -- Friv"ol*er, Friv"ol*ler, n. [All Colloq.] [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
frivol v 1: act frivolously [syn: frivol, trifle]