a fibrocartilaginous disc serving as a cushion between all of the vertebrae of the spinal column (except between the first two) | a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin |
| 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 series of vertebrae forming the axis of the skeleton and protecting the spinal cord |
| a small sharp-pointed tip resembling a spike on a stem or leaf |
| any sharply pointed projection |