The Collaborative International Dictionary of English v.0.48:

Ostentate \Os"ten*tate\, v. t. [L. ostentatus, p. p. of
   ostentare, v. intens. fr. ostendere. See Ostent.]
   To make an ambitious display of; to show or exhibit
   boastingly. [R.] --Jer. Taylor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ostentate
    v 1: display proudly; act ostentatiously or pretentiously; "he
         showed off his new sports car" [syn: flaunt, flash,
         show off, ostentate, swank]