third-party

1 of 2

adjective

third-par·​ty ˈthərd-ˈpär-tē 

1

: of, relating to, or involving a third party

third-party insurance

2

: of, relating to, or being software that is created by a vendor to be compatible with the products of another vendor

third party

2 of 2

noun

1

: a person other than the principals

a third party to a divorce proceeding

insurance against injury to third parties

2

a

: a major political party operating over a limited period of time in addition to two other major parties in a nation or state normally characterized by a two-party system

b

: minor party

Examples of third-party in a Sentence

Recent Examples on the Web

Adjective

The Mountain West commissioned a third-party investigation into the allegations against Fleming, and determined that sufficient evidence could not be found to assign discipline. —Jackson Thompson, FOXNews.com, 14 Dec. 2025

If your package is marked as undeliverable or missing, then contact Amazon or the third-party seller. —Riley Rourke, CBS News, 12 Dec. 2025

Noun

Even so, the Society for Ethics in Egg Donation and Surrogacy, a nonprofit that releases standards for surrogacy and egg donation, still advises that a third party hold the escrow to protect intended parents and surrogates. —Alexandra Chaidez, NBC news, 18 Dec. 2025

OpenAI can now also develop some products with third parties. —Ashley Capoot,mackenzie Sigalos, CNBC, 17 Dec. 2025

Word History

First Known Use

Adjective

1901, in the meaning defined at sense 1

Noun

1641, in the meaning defined at sense 1

Kids Definition

third party

noun

1

: a person other than the main participants

a third party to the legal proceedings

2

a

: a political party operating usually for a limited time in addition to the two major parties in a 2-party system

b

: minor party

Legal Definition

third party

see party sense 1a, b