“Porcupine,” formerly “porke despyne,” comes from the Old French porc-espin, literally “spiny pig” or “thorny pig,” from Latin porcus “hog” (from PIE root porko- “young pig”) + spina, “thorn, spine.”
Much like raccoon, the word porcupine has been subject to all manner of letter-salad spellings, including portepyn, porkpen, porkenpick, porpoynt, and porpentine (which appears in Hamlet, “Like quills upon the fretful porpentine”).
Useless Etymology 