2、词源不详。可能来自beast, 野兽，或boast, 吹嘘。
2、late 15c., unexplained alteration of Middle English boistous (c. 1300)"rough, coarse (as of food), clumsy, violent,"which is of unknown origin, perhaps from Anglo-French bustous"rough (road),"which is perhaps from Old French boisteos"curved, lame; uneven, rough"(Modern French boiteux), itself of obscure origin. Another guess traces it via Celtic to Latin bestia. Used of persons from 1560s. Related: Boisterously; boisterousness.