bivouac

Short definition from Wiktionary

Noun

1. 1
   An encampment for the night, usually without tents or covering.
2. 2
   Any temporary encampment.
3. 3
   A temporary shelter constructed generally for a few nights.
4. 4
   The watch of a whole army by night, when in danger of surprise or attack.
5. 5
   A structure formed by migratory ants out of their own bodies to protect the queen and larvae.

Verb

1. 1
   To set up camp.
2. 2
   To watch at night or be on guard, as a whole army.
3. 3
   To encamp for the night without tents or covering.