proof coin

noun

: a coin not intended for circulation but struck from a new, highly-polished die on a polished planchet and sometimes in a metal different from a coin of identical denomination struck for circulation

As one of the world's largest proof coins, it contains an enormous four full ounces of pure silver!

—The Numismatist, April 1988

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!