bivouac \ BIV-wak, BIV-uh-wak \ noun – An encampment for the night, usually under little or no shelter. intransitive verb – To encamp for the night, usually under little or no shelter. Origin: Bivouac comes from French bivouac, from German Beiwache, “a watching or guarding,” from bei, “by, near” + wachen, “to watch.”