Word Origin & History
boastmid-13c., from Anglo-Norm. bost, probably via Scandinavian (cf. Norw. baus "proud, bold, daring"), from P.Gmc. *bausia "to blow up, puff up, swell" (cf. dial. Ger. baustern "to swell," M.Du. bose, Du. boos "evil, wicked, angry," O.H.G. bosi "worthless, slanderous," Ger. böse "evil, bad, angry"),
from PIE *bhou-, variant of base *bheu- "to grow, swell" (see
be). The notion apparently is of being "puffed up" with pride; cf. O.E. belgan "to become angry, offend, provoke," belg "anger, arrogance," from the same root as bellows and
belly (q.v.).