'Boyau' definitions:
- Boyau \Boy"au\, n.; pl. Boyaux or Boyaus. [F. boyau gut, a
long and narrow place, and (of trenches) a branch. See
Bowel.] (Fort.)
A winding or zigzag trench forming a path or communication
from one siegework to another, to a magazine, etc.
[1913 Webster]
