Source : Webster's Revised Unabridged Dictionary (1913)

Spine \Spine\, n. [L. spina thorn, the spine; akin to spica a
   point: cf. OF. espine, F. ['e]pine. Cf. {Spike}, {Spinet} a
   musical instrument, {Spinny}.]
   1. (Bot.) A sharp appendage to any of a plant; a thorn.

   2. (Zo["o]l.)
      (a) A rigid and sharp projection upon any part of an
          animal.
      (b) One of the rigid and undivided fin rays of a fish.

   3. (Anat.) The backbone, or spinal column, of an animal; --
      so called from the projecting processes upon the
      vertebr[ae].

   4. Anything resembling the spine or backbone; a ridge.

Source : WordNet®

spine
     n 1: the series of vertebrae forming the axis of the skeleton and
          protecting the spinal cord; "the fall broke his back"
          [syn: {spinal column}, {vertebral column}, {backbone}, {back},
           {rachis}]
     2: any pointed projection [syn: {spur}]
     3: a sharp-pointed tip on a stem or leaf [syn: {thorn}, {prickle},
         {pricker}, {sticker}]
     4: a sharp rigid animal process or appendage; as a porcupine
        quill or a ridge on a bone or a ray of a fish fin