trou-de-loup

English Wikipedia has an article on:

trou de loup

Wikipedia

troup de loup

French, literally "wolf-hole".

trou-de-loup (plural trous-de-loup)

1. (military, historical) A pit in the form of an inverted cone or pyramid, constructed as an obstacle to the approach of an enemy, and having a pointed stake in the middle.

• tiger pit
• traphole

• “trou-de-loup”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.