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

Some products are tested by third-party labs to ensure their safety and accurate labeling. —Merve Ceylan, Health, 28 Sep. 2025

The district also confirmed that Roberts underwent a third-party comprehensive background check. —Charna Flam, PEOPLE, 27 Sep. 2025

Noun

Pending review of the documents, the two groups could file a derivative lawsuit, which allows shareholders to act on behalf of a company and sue the corporation’s own directors and officers, as well as other third parties who may have harmed the company. —Jon Blistein, Rolling Stone, 25 Sep. 2025

Arbitration, a process involving two sides presenting a case for a third party to decide, started this week between the Milwaukee Police Association and the city of Milwaukee. —Kelli Arseneau, jsonline.com, 25 Sep. 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