chevaux-de-frise
The Concise Oxford Dictionary of English Etymology
© The Concise Oxford Dictionary of English Etymology 1996, originally published by Oxford University Press 1996.
chevaux-de-frise spiked contrivance for obstructing enemy troops. XVII. — F., lit. ‘horses of Friesland’, so called because they were first used by the Frisians to compensate for their lack of cavalry.