The Collaborative International Dictionary of English v.0.48:
Boastful \Boast"ful\, a. Given to, or full of, boasting; inclined to boast; vaunting; vainglorious; self-praising. -- Boast"ful*ly, adv. -- Boast"ful*ness, n. [1913 Webster]WordNet (r) 3.0 (2006):
boastfully adv 1: in a boastful manner; "he talked big all evening" [syn: boastfully, vauntingly, big, large]