"coarse, detrital material" apparently deposited by powerful operation of water on a vast scale, 1819, from Latin diluvium "flood, inundation," from diluere "wash away," from dis- "away" (see dis-) + -luere, combining form of lavere "to wash" (from PIE root *leue- "to wash"). Middle English had diluvie "a flood, a deluge" (early 14c.) from Old French diluvie and directly from the Latin word.
