spine in WordNet English dictionary

1. any sharply pointed projection
   spur  spine  acantha 
   
2. the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
   "the fall broke his back"
   spinal column  vertebral column  spine  backbone  back  rachis 
   
3. 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"
   spine  backbone 
   
4. a small sharp-pointed tip resembling a spike on a stem or leaf
   spine  thorn  prickle  pricker  sticker  spikelet 
   
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
   spine