bivouac /ˈbɪv.u.æk/noun 5verb 3forms 5 noun5 •An encampment for the night, usually without tents or covering. •Any temporary encampment. •A temporary shelter constructed generally for a few nights.Behold the Mansion reared by Daedal Jack! See the Malt stored in many a plethoric sack, In the proud cirque of Juan's bivouac! — 1977 •A structure formed by migratory ants out of their own bodies to protect the queen and larvae.Army ants (genus Eciton) migrating and gathering in a bivouac. — 2026 •(old-fashioned) The watch of a whole army by night, when in danger of surprise or attack. verb3 •To set up camp.We'll bivouac here tonight. •To encamp for the night without tents or covering. •To watch at night or be on guard, as a whole army. formsbivouacked · bivouacing · bivouacking · bivouacks · bivouacs