Definition of: spine

(spīn) noun
1. The spinal column of a vertebrate; backbone.
2. Zool. Any of various hard, pointed outgrowths on the bodies of certain animals, as the porcupine and starfish; a spicule; the fin ray of a fish.
3. Bot. A stiff, short-pointed woody process on the stems of certain plants, as the honey locust; thorn.
4. The back of a bound book.
5. A projecting eminence or ridge.
6. Any slender, thornlike process, as of a vertebra or nerve.
7. The central ridge on the underside of a horse's hoof. [<OF espine <L spina spine, thorn]