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

The firm has said its methodologies are audited annually by an independent third party.

From The Wall Street Journal • Apr. 17, 2026

And he repeatedly stated that Iran had agreed to the removal of its enriched uranium from the country, either to the United States or to a third party.

From Los Angeles Times • Apr. 17, 2026

The lawsuits attempted to skirt around Section 230 by suing on the basis of the platform’s internal features, not third party content posted on the platforms.

From Salon • Apr. 16, 2026

We don’t actually know 100% what she/he said or did — only that she reacted strongly and that response was reported to a third party.

From MarketWatch • Apr. 13, 2026

Any third party whom you might make their commander cannot immediately seize enough authority to harm you.

From "The Prince" by Niccolò Machiavelli

Related Words

• mediator