<p><strong>Noun</strong></p><ul><li>the spinal or vertebral column; backbone.</li><li>any backbonelike part.</li><li>a stiff, pointed process or appendage on an animal, as a quill of a porcupine, or a sharp, bony ray in the fin of a fish.</li><li>something, as a quality or trait, that constitutes a principal strength; resolution; stamina; backbone: a situation that would test a person's spine.</li><li>a ridge, as of ground or rock.</li><li>a sharp-pointed, hard or woody outgrowth on a plant; thorn.</li><li>Bookbinding: the back of a book cover or binding, usually indicating the title and author.</li></ul>