spine

the series of vertebrae forming the axis of the skeleton and protecting the spinal cord

the fall broke his back

any sharply pointed projection

a small sharp pointed tip resembling a spike on a stem or leaf

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

the title and author were printed on the spine of the book

a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin