n.
     - a series of vertebrae extending from the skull to the small of the back, enclosing the spinal cord and providing support for the thorax and abdomen; the backbone.
 - a central feature or main source of strength.
 - the part of a book's jacket or cover that encloses the inner edges of the pages.
 - chiefly Zoology  & Botany  a prickle or other hard pointed projection or structure.
 - 
(also pay spine)
 a linear pay scale operated by some large organizations that allows flexibility for local and specific conditions.
 
 
  Derivative
  
  Etymology
  ME: shortening of OFr. espine, or from L. spina ‘thorn, backbone’.