keyhole urchin
noun
Definition of keyhole urchin
: a flat sea urchin of the order Exocycloida with long narrow apertures occurring near the margin of the test
Explore Merriam-Webster
There's more!
Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.
Start your free trial today and get unlimited access to America's largest dictionary, with:
- More than 250,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Seen and Heard
What made you want to look up keyhole urchin? Please tell us where you read or heard it (including the quote, if possible).
Writing? Check your grammar now!