spine

1. A series of bones situated at the back from the head to the pelvis of a human, or from the head to the tail of an animal, enclosing the spinal cord and providing support for the thorax and abdomen.
2. Courage or assertiveness. (figuratively)
3. Something resembling a backbone, such as a ridge, or a long, central structure from which other structures radiate.
4. The narrow, bound edge of a book that encloses the inner edges of the pages, facing outwards when the book is on a shelf and typically bearing the title and the author's and publisher's name.
5. A pointed, fairly rigid protuberance or needlelike structure on an animal, shell, mushroom or plant. The botanical term technically refers to such a structure derived from a leaf or part of a leaf.
6. The heartwood of trees.
7. A linear payscale operated by some large organizations that allows flexibility for local and specific conditions.
8. A tall mass of viscous lava extruded from a volcano.

Plural spines