spine

noun11

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.

   • If you attentively regard almost any quadruped's spine, you will be struck with the resemblance of its vertebrae to a strung necklace of dwarfed skulls. — 1851
2. •
   Something resembling a backbone, such as a ridge, or a long, central structure from which other structures radiate.
3. •
   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.

   • The spine is the book's backbone. Because the spine is generally all you can see when a book is on the shelf, the spine displays the title and author of the book and is often ornately decorated. — 1994
4. •
   A central part which supports a whole; core.
5. •
   (figurative) Courage or assertiveness.

   • Trademark Owners will nevertheless try to dictate how their marks are to be represented, but dictionary publishers with spine can resist such pressure. — 2001
6. •
   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.

   • The male, as Dr. Gunther informs me, has a cluster of stiff, straight spines, like those of a comb, on the sides of the tail. — 1871
7. •
   Ellipsis of dendritic spine.

   • Spines are distinguished by the presence of globular tips called spine heads; when spines are present, the synapses innervating dendrites are made from these heads. — 2008
8. •
   A linear payscale operated by some large organizations that allows flexibility for local and specific conditions.
9. •
   A tall mass of viscous lava extruded from a volcano.
10. •
    The heartwood of trees.
11. •
    The stiffness of an arrow.