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

Similar word(s): back, backbone, rachis

Definition categories: body

2. any sharply pointed projection

Similar word(s): acantha, spur

Definition categories: shape, projection

3. a small sharp-pointed tip resembling a spike on a stem or leaf

Similar word(s): pricker, prickle, spikelet, sticker, thorn

Definition categories: plant, aculeus

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

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

Similar word(s): backbone

Definition categories: man–made, part, portion

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

Definition categories: animal, appendage, outgrowth, process