How do you spell Spine

Available Definitions:
1)  n. - A sharp appendage to any of a plant; a thorn.
2)  n. - A rigid and sharp projection upon any part of an animal.
3)  n. - One of the rigid and undivided fin rays of a fish.
4)  n. - The backbone, or spinal column, of an animal; -- so called from the projecting processes upon the vertebrae.
5)  n. - Anything resembling the spine or backbone; a ridge.