D defs.my
Entry 1 sense Webster, 1913

Boyau

· Boy·au · IPA /ˈbwɑːjəʊ/
01 n. A winding or zigzag trench forming a path or communication from one siegework to another, to a magazine, etc.
pl. Boyaux, Boyaus
  1. 1.
    A winding or zigzag trench forming a path or communication from one siegework to another, to a magazine, etc.(Fort.)