Having many spines. / Spine-like; spiny. / (obsolete) Of a person: difficult to deal with, prickly. / (rare) Of a subject: providing many difficulties, thorny. / (anatomy) Having a sharp projection.

plural of spinous process

(anatomy) A bony process of a vertebra that projects posteriorly from the neural arch and serves as attachment for muscles and ligaments.

plural of spinous spider crab

European spider crab

The quality of being spinous.