billow

From Middle English bilwe, borrowed from Old Norse bylgja, from Proto-Germanic bulgijō. Cognates include Danish bølge (“wave”); Norwegian Bokmål bølge (“wave”), Norwegian Nynorsk bylgje (“wave”); Swedish bölja (“wave”); German Low German Bulge, Bulg, Bülg (“billow, wave”); German Bulge (“billow, wave”). Compare bellow, bawl.