The Collaborative International Dictionary
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.
Wiktionary
n. 1 (context military English) A small trench or ditch, typically built in a zigzag pattern, serving to connect or provide communication between two trenches, particularly the rear and front lines. 2 A line, drawn winding about, in order to enclose several tracts of land, or to attack some works.
Usage examples of "boyau".
So packing our sacks we walked down the boyau about nightfall to the poste du commandement, where we left all our equipment and got our individual permissions.
This we did about midnight and, while half the regiment was noisily commencing its journey back to Orléans, the rest came up through the boyaux to their old emplacements, where after a night on guard we now are.
Marched back down the boyaux to the glassworks at La Neuvillette, and then continued on down the dark towpath of the canal to Courcelles, on the outskirts of Reims, where we were comfortably cantonnés for the night.
Walked through the pine groves at the summit of the crest and then came out through a deep-cut boyau to a magnificent spectacle.
We formed a long file, one man with a pick and one with a shovel at five yard intervals down the open northern slope and started digging an immense boyau to rush troops up through for the attack.
We broke camp about 11 o'clock the night of the 24th, and marched up through ruined Souain to our place in one of the numerous boyaux where the troupes d'attaque were massed.
Amid the most infernal roar of every kind of fire-arms and through an atmosphere heavy with dust and smoke, we marched up through the boyaux to the tranchées de départ.
Meanwhile, bridges had been thrown across trenches and boyaux, and the artillery, leaving the emplacements where they had been anchored a whole year, came across and took position in the open, a magnificent spectacle.
I had only two days to work in, days full of boyau-digging with pick and shovel, but by making an effort I managed to compose the poem in time.