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

Alaska sends the four highest finishers in its nonpartisan primary onto the general election – all but ensuring that the general includes candidates from both parties and even independents or third-party hopefuls. —Tom Charron, Mercury News, 6 Mar. 2026

Cymbiotika’s ingredients are all third-party tested and GMP-certified, too. —Brianna Peters, Vogue, 6 Mar. 2026

Noun

Unlike a partisan primary, all the candidates — Republicans, Democrats and third party candidates — will be on the same ballot for voters in the special election. —Sarah Kallis, NPR, 10 Mar. 2026

Please do not buy third party tickets. —Hannah Hudnall, USA Today, 9 Mar. 2026

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 also:

party sense 1a, b