Thanks, belMarduk.

Foussé is not a modern French word. The word fossé means a trench.

One dictionary I looked at via Google books said that foussé was an archaic spelling of fossé. It's from Latin fossa 'ditch, trench'. It is interesting that ditch and dike are related: one is from Old English díc and the other from Old Norse díki 'ditch', from the same PIE root, *dhīgʷ- 'to stick, fix' (also IEW), where we get dig.

Ceci n'est pas un seing.