rodent noted for its stout, clumsy body and the defensive spines or quills that cover the body and tail, c. 1400, porke despyne, from Old French porc-espin (early 13c., Modern French porc-épic), literally "spine hog," from Latin porcus "hog" (from PIE root *porko- "young pig") + spina "thorn, spine" (see spine). The word had many forms in Middle English and early Modern English, including portepyn (influenced by port "to carry," as though "carry-spine"), porkpen, porkenpick, porpoynt, and Shakespeare's porpentine (in "Hamlet"). The same notion forms the name in other languages (Dutch stekel-varken, German Stachelschwein).
The spines grow mostly on the rump and back of the broad flat tail ; they are quite loosely attached, and when the animal slaps with its tail (its usual mode of defense) some quills may be flirted to a distance. Something like this, no doubt, gives rise to the popular notion that the porcupine "shoots" its quills at an enemy. [Century Dictionary]
May (9 years old)—"Papa, things pertaining to a horse are equine, to cows bovine, to cats feline, to dogs canine, but to hogs, is what?"
Fay (5 years)—"Porcupine, O tourse."
[Health, August 1904]
"afflicted with rickets," 1797, from rachitis (1727), medical Latin name for the bone disease, from Late Greek rhakhitis (nosos) "rachitic (disease), inflammation of the spine," from Greek rhakhis "spine, back," metaphorically "ridge (of a mountain), rib of a leaf" (see rachio-).
word-forming element meaning "of or involving the sacrum," the bone at the base of the spine. As in sacro-iliac "pertaining to the sacrum and the ilium."
"cut of animal meat and bones," usually involving the neck and forepart of the spine, 1560s, of unknown origin; perhaps from some resemblance to rack (n.1). Compare rack-bone "vertebrae" (1610s).