barrel sponge

noun

: any of various large, usually cylindrical sponges (genus Xestospongia of the class Demospongiae) found especially on tropical coral reefs

I pass over the largest, healthiest barrel sponge I've ever seen—it seems plausible that I could fit inside it …

—Scott Edler, Washington Post, 21 Oct. 2012

Word History

First Known Use

1979, in the meaning defined above

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!