Spine is a word with several meanings. Most common is reference to a sharp, pointed or needle-like structure, such as the spines on a cactus plant.
A rather different meaning refers to the column of vertebral bones that form the backbone or "spine" of vertebrate organisms, supporting the body and protecting the spinal cord from damage. Alluding to this meaning of "spine" as a principal or central element in support of a body is the sense that a mountain range forms the 'spine' of an island or continent. Also, the spine of a book is the part where the inside edges of all the pages are joined and bound together; that face of a bound publication seen on shelved books.
See the following entries for specific details:
