bivouac vs bivvy

bivouac

noun
  • An encampment for the night, usually without tents or covering. 

  • Any temporary encampment. 

  • A temporary shelter constructed generally for a few nights. 

  • A structure formed by migratory ants out of their own bodies to protect the queen and larvae. 

verb
  • To encamp for the night without tents or covering. 

  • To set up camp. 

  • To watch at night or be on guard, as a whole army. 

bivvy

noun
  • A small tent or shelter. 

verb
  • To erect, or to stay in, such a tent or shelter. 

How often have the words bivouac and bivvy occurred in a corpus of books? (source: Google Ngram Viewer )