spinous

adjective5

1. •
   Having many spines.

   • The organs are simple and spinous, the spines small distally on the organ, larger proximally. — 1968
2. •
   Spine-like; spiny.
3. •
   Having a sharp projection.

   • the spinous processes of the lumbar vertebrae
4. •
   (rare) Of a subject: providing many difficulties, thorny.

   • The spinous problem shifted from the how to find minima efficiently to what method should be employed to provide a better connection between the topography and the dynamics on the surface. — 2006
5. •
   (no longer used) Of a person: difficult to deal with, prickly.

   • He had the rough magnanimity of the old English vein, mellowed into tenderness and dashed with a flexible and spinous humor. — 1836