The Collaborative International Dictionary
trapholes
Trou-de-loup \Trou"-de-loup"\, n.; pl. Trous-de-loup. [F. trou hole + de of + loup wolf.] (Mil.) 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. The pits are called also trapholes.
Wiktionary
trapholes
n. (plural of traphole English)