third party

American  

noun

third parties plural

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.

---

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

---

adjective

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

   third-party insurance

Other Word Forms

Noun Inflected Forms

• third parties
  plural

Etymology

Origin of third party

An Americanism dating back to 1795–1805

Example Sentences

As third party delivery services such as DoorDash grew in popularity, Pizza Hut fell behind without the advantage of delivery convenience, said Aneurin Canham-Clyne, a reporter for trade publication Restaurant Drive.

From Los Angeles Times • Jun. 16, 2026

Anthropic described the loophole discovered by this third party -- identified by several media outlets as Amazon -- as "narrow" and said the software vulnerabilities it exposed were "minor."

From Barron's • Jun. 14, 2026

The notorious bidding war for a Palm Beach estate between Trump and Jeffrey Epstein involved a third party.

From Salon • Jun. 9, 2026

He added that McCullagh's attempt to implicate an innocent third party - Natalie's ex-boyfriend - was another factor.

From BBC • Jun. 3, 2026

A man that thinks anything he dont understand all about must be crooked and that first chance he gets he’s morally bound to tell the third party what’s none of his business to tell.

From "The Sound and the Fury" by William Faulkner

Related Words

• mediator