Webster's Revised Unabridged Dictionary · 1913

Spine

Spine , noun

[Latin spina thorn, the spine; akin to spica a point: compare Old French espine, French épine. Compare Spike, Spinet a musical instrument, Spinny.]

1.
(Botany) A sharp appendage to any of a plant; a thorn.
2.
(a) (Zoology) A rigid and sharp projection upon any part of an animal.
(b)
(Zoology) One of the rigid and undivided fin rays of a fish.
3.
(Anatomy) 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.