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 use of advertising cookies sent by third-party servers is common on the Internet. —Hazlitt, 6 Feb. 2026

Purity The supplements are made in a Good Manufacturing Practice facility, and are third-party lab tested for purity to ensure confidence in what the label says. —Pubsubhub User, Chicago Tribune, 6 Feb. 2026

Noun

Offer availability, placement, and display are determined by the third party and may be influenced by compensation and other factors. —Jasmin Suknanan, CNBC, 10 Feb. 2026

Gift cards can be sold by a merchant for its own goods or by a third party. —Roxana Popescu, San Diego Union-Tribune, 9 Feb. 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 party sense 1a, b