n.1 any rodent of the family Hystricidae native to Africa, Asia, and SE Europe, or the family Erethizontidae native to America, having defensive spines or quills.
2 (attrib.) denoting any of various animals or other organisms with spines.
Phrases and idioms:
porcupine fish a marine fish, Diodon hystrix, covered with sharp spines and often distending itself into a spherical shape.
Derivatives:
porcupinish adj. porcupiny adj.
Etymology: ME f. OF porc espin f. Prov. porc espi(n) ult. f. L porcus pig + spina thorn