Real Dictionary

porcupine
countable noun: A porcupine is an animal with many long, thin, sharp spikes on its back that stick out as protection when it is attacked.

Porcupine in American English
any of a terrestrial Old World family (Hystricidae) or an arboreal New World family (Erethizontidae) of rodents, having coarse hair mixed with long, stiff, sharp spines that can be erected
river in N Yukon Territory, Canada, flowing into the Yukon River in NE Alas.: 590 mi (949 km)
noun: any of several rodents covered with stiff, sharp, erectile spines or quills, as Erethizon dorsatum of North America

porcupine in British English
noun: any of various large hystricomorph rodents of the families Hystricidae, of Africa, Indonesia, S Europe, and S Asia, and Erethizontidae, of the New World. All species have a body covering of protective spines or quills