cunette
Cunette (noun) means a narrow ditch cut into a moat, used to drain water away or to slow down attackers.
Etymology
Comes from French cunette (also possibly lacunette), from Italian cunetta ("cunette"), said to derive from lacunetta, a diminutive of lacuna ("ditch; lagoon; gap"), from Latin lacūna ("hole, pit; cavity, cleft, hollow, opening; gap, void"), from lacus ("lake"), from Proto-Indo-European *lókus ("lake, pool").