[Fr., from L. porcus, a hog; and spina, a thorn. ] A nocturnal rodent quadruped, about two feet long, having on the head and neck a crest of long hairs, very short hair on the legs and muzzle, and the other parts covered with spines or quills, some a foot long, which, when excited, the animal raises almost at right angles with the body. Porcupines generally inhabit warm or tropical regions. The common or crested of southern Europe and northern Africa, and the Canadian or North American, are the best-known species.