Bearing or covered with spines, thorns, or similar stiff projections. (adjective)
Shaped like a spine. (adjective)
Difficult; troublesome. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "spiny" in a sentence
"I mean, discipline -- if ever you'd known discipline -- in the police if you like -- anything -- anywhere where there's what we used to call spiny de cor."
"The Houses of Parliament runs one; another casts its spooky glow over Buckingham Palace gardens a sub- Saharan moth called the spiny bollworm puzzled scientists until they discovered a state delegation from Tanzania had stayed with the Queen the week before."
"Among the fossils found here are acanthodians - the so-called "spiny sharks" which are thought to be the oldest vertebrates to possess true teeth - and what Blais and colleagues consider to be a chondrichthyan, or an early member of the group of cartilaginous fish which includes sharks, skates, and rays today."