spine noun [L. spina thorn, the spine; akin to spica a point: cf. OF. espine, F. épine. Cf. Spike, Spinet a musical instrument, Spinny.]

1. (Bot.) A sharp appendage to any of a plant; a thorn.

2. (Zool.)

(a) A rigid and sharp projection upon any part of an animal.

(b) One of the rigid and undivided fin rays of a fish.

3. (Anat.) The backbone, or spinal column, of an animal; – so called from the projecting processes upon the vertebrae.

4. Anything resembling the spine or backbone; a ridge.

-- Websters 1913