third party

American  

noun

1. any party to an incident, case, quarrel, etc., who is incidentally involved.

2. (in a two-party system) a political party formed as a dissenting or independent group from members of one or both of the two prevailing major parties.

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third party British  

noun

1. a person who is involved by chance or only incidentally in a legal proceeding, agreement, or other transaction, esp one against whom a defendant claims indemnity

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adjective

1. insurance providing protection against liability caused by accidental injury or death of other persons or damage to their property

   third-party insurance

Etymology

Origin of third party

An Americanism dating back to 1795–1805

Example Sentences

There is a green party, the ADPD, but no third party has held even a seat in Malta's parliament since before independence in 1964.

From Barron's • May 31, 2026

"A planned attack preceded by reconnaissance, and which was ordered by a third party acting on behalf of the Iranian state," he said.

From BBC • May 18, 2026

Genesis Minerals “remains the obvious third party with clear strategic benefits in the Leonora region,” Hissey says.

From The Wall Street Journal • May 5, 2026

In Rockefeller’s defense, as a business owner, you would rather have a job done by your own trusted people than pay an unknown third party to handle the task.

From Barron's • May 2, 2026

"Yes, sir, he put through the sale—though he made it clear that he was buying Soldier Island for a third party, unnamed."

From "And Then There Were None" by Agatha Christie

Related Words

• mediator