Merriam-Webster online, March 16, 2017: LCSH; (Spillways) RAMEAU; (Déversoirs) spillway (def. 1: a passage (such as a paved apron or channel) for surplus water over or around a dam or similar obstruction) floodway (an area or channel provided as an emergency course to divert floodwaters (as from more populous regions)) http://id.loc.gov/authorities/subjects/sh85126646 lcsh http://data.bnf.fr/ark:/12148/cb11979887k rameau