1. The series of vertebrae forming the axis of the skeleton and protecting the spinal cord
   "the fall broke his spine";
   - spinal column, vertebral column, backbone, back, rachis [technical]
    
2. Any sharply pointed projection
   "The spine on the plant's stem served as a defence against herbivores";
   - spur, acantha
    
3. A small sharp-pointed tip resembling a spike on a stem or leaf
   "The rose's spines caught on her sleeve as she pruned the bush";
   - thorn, prickle, pricker
    
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";
   - backbone
    
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
   "The porcupine's spines provide an effective defence against predators"

Derived forms: spines

Type of: aculeus, appendage, outgrowth, part, portion, process, projection, skeletal structure

Part of: axial skeleton, book, volume

Encyclopedia: Spine