1. (New World porcupine) An arboreal, herbivorous rodent (family Erethizontidae) that has a thickset body, short legs, long claws, and some hairs modified to form barbed spines. In tree porcupines (Coenus species) the tail is prehensile. There are four genera with 17 species found throughout North America and tropical South America.

2. (Old World porcupine) A nocturnal, herbivorous, burrowing rodent with a long tail (family Hystricidae), similar in appearance to the New World porcupine, that moves slowly and relies for defence mainly on the rustling sound made by its spines. There are four genera with about 16 species found throughout Africa, Italy, and southern Asia.