a small european insectivore (erinaceus europaeus), and other allied species of asia and africa, having the hair on the upper part of its body mixed with prickles or spines. it is able to roll itself into a ball so as to present the spines outwardly in every direction. it is nocturnal in its habits, feeding chiefly upon insects.-the canadian porcupine.-a species of medicago (m. intertexta), the pods of which are armed with short spines; -- popularly so called.-a form of dredging machine.