Source : Webster's Revised Unabridged Dictionary (1913)

Spinous \Spi"nous\, a.
   1. Spinose; thorny.

   2. Having the form of a spine or thorn; spinelike.

   {Spinous process of a vertebra} (Anat.), the dorsal process
      of the neural arch of a vertebra; a neurapophysis.

Source : WordNet®

spinous
     adj : shaped like a spine or thorn [syn: {acanthoid}, {acanthous}]