cunette

1. (military) A trench dug in a moat to allow for drainage, or as an extra obstacle for attackers.Examples: "Ford's Ravelin.—Completed in its ditch, ſluices, cunette, aqueducts, ſcarp, and counterſcarp walls; […]"; "Nor was anything done at San Pablo except the cutting of two cunettes necessary for working with heavy machinery, and the projection of a plane for a passage under the Panama Railway, by which the excavations made at K. 35.700 could be carried to the banks of the Chagres."; "In principle, cunettes are carried out with a view to substituting poor load bearing and highly compressible strata with sand with a view to a) reducing residual settlements and b) improving stability."