The noun SPINE has 5 senses: 1. the series of vertebrae forming the axis of the skeleton and protecting the spinal cord. 2. any sharply pointed projection. 3. a small sharp-pointed tip resembling a spike on a stem or leaf.4. the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelved. 5. a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin.yponyms (each of the following is a kind of spine): notochord (a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates). chine (backbone of an animal).