What is the meaning of Boyau?

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.

A line, drawn winding about, in order to enclose several tracts of land, or to attack some works.

gut, intestine (of an animal, or, informally of a human)

catgut, gut

communication trench, boyau

hose, e.g. a firehose

Source: wiktionary.org