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The Collaborative International Dictionary
Berain

Berain \Be*rain\, v. t. [imp. & p. p. Berained; p. pr. & vb. n. Beraining.] To rain upon; to wet with rain. [Obs.]
--Chaucer.

Wiktionary
berain

vb. (context transitive English) To rain upon; wet with rain; moisten.