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

When you set up biometric authentication to confirm your identity when paying for purchases, a digital translation of your face or palm, say, is created and stored by the merchant or a third party.

From The Wall Street Journal • Mar. 20, 2026

Lawyers already are barred under the State Bar’s rules from allowing a third party to dictate case strategy and are barred in many cases from sharing legal fees with a nonlawyer.

From Los Angeles Times • Mar. 17, 2026

Any prospective heirs will then have to rely on their own skills to build their finances, rather than relying on a third party.

From MarketWatch • Mar. 16, 2026

Much of the growth came from the sale of newly originated leases to a third party, a new tactic for the company.

From Barron's • Feb. 27, 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