What Does It Mean?

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From our dictionary:
biv•ou•ac

(biv'OOoak", biv'wak),
n., v., -acked, -ack•ing.

n.
1. a military encampment made with tents or improvised shelters, usually without shelter or protection from enemy fire.
2. the place used for such an encampment.

v.i.
to rest or assemble in such an area; encamp.