Definition of spine

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