red clay

noun

1

: clay that usually owes its reddish color to oxide of iron

2

: a slowly accumulating abysmal deposit covering some 55,000,000 square miles of the deepest parts of the ocean bottom and consisting of the insoluble residual material of volcanic and meteoritic or cosmic dust mingled with nodules of manganese oxide, crystals of the zeolite phillipsite, sharks' teeth, the siliceous tests of Radiolaria, and other resistant organic debris

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!