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.

---

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

Etymology

Origin of third party

An Americanism dating back to 1795–1805

Example Sentences

Appeared in the April 3, 2026, print edition as 'Amazon to Apply Fuel Surcharge Of 3.5% to Third-Party Sellers'.

From The Wall Street Journal • Apr. 2, 2026

“CMS is concerned about the marketing practices of all entities, including Third-Party Marketing organizations,” Kathryn A. Coleman, director of the agency’s Medicare Drug and Health Plan Contract Administration Group, wrote in the letter.

From Seattle Times • Nov. 4, 2022

We will not be silenced until Bobby Kotick has been replaced as CEO, and continue to hold our original demand for Third-Party review by an employee-chosen source.

From The Verge • Nov. 16, 2021

Third-Party Outsourcers These advisers put money into more sophisticated funds whose goal is total return and not beating a benchmark.

From New York Times • Jul. 18, 2014

The conference ended with an agreement to support a Third-Party movement directed by Jenkins.

From Secret Armies The New Technique of Nazi Warfare by Spivak, John L.

Related Words

• mediator