means A large rodent covered in sharp, stiff quills that it raises to deter predators.

from From Old French 'porc espin,' literally 'spiny pig' — 'porc' (pig) plus 'espin' (spine, thorn), tracing back to Latin 'porcus' (pig) and 'spina' (thorn). Despite the name, it's no relative of the pig; medieval onlookers just saw a stout, bristling beast and reached for the nearest farmyard comparison. The English spelling wandered for centuries — 'porkpen,' 'porpentine,' even Shakespeare's 'fretful porpentine' — before settling on the form we know.