Cheval-de-frise
Cheval-de-frise , noun
[French; cheval horse + Frise Friesland, where it was first used.]
(Military) A piece of timber or an iron barrel traversed with iron-pointed spikes or spears, five or six feet long, used to defend a passage, stop a breach, or impede the advance of cavalry, etc.
Obstructions of chain, boom, and cheval-de-frise.