The Collaborative International Dictionary of English v.0.48:

Gallivant \Gal"li*vant\, v. i. [From Gallant.]
   To play the beau; to wait upon the ladies; also, to roam
   about for pleasure without any definite plan. [Slang]
   --Dickens.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gallivant
    v 1: wander aimlessly in search of pleasure [syn: gallivant,
         gad, jazz around]