costar

American  

[koh-stahr, koh-stahr] / ˈkoʊˌstɑr, ˈkoʊˈstɑr /

Or co-star

noun

1. a performer, especially an actor or actress, who shares star billing with another.

2. a performer whose status is slightly below that of a star.

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verb (used without object)

costarred, costarring

1. to share star billing with another performer.

2. to receive billing of slightly less status than that of a star.

verb (used with object)

costarred, costarring

1. to present (two or more actors) as having equal billing or prominence.

2. to present as having slightly less status than that of a star.

Etymology

Origin of costar

An Americanism dating back to 1915–20; co- + star

Example Sentences

Instead, she at first finds Mr. Hamm’s “Mad Men” costar, a touchy John Slattery, living out of his garage.

From The Wall Street Journal • Jan. 29, 2026

When he recalls the moment he told Candy that Jim Belushi died in 1981, Candy’s “SCTV” costar Dave Thomas tearfully recalls his friend saying, “Oh God, it’s starting.”

From Salon • Oct. 12, 2025

Mirren and Brosnan are not the first to push back on the idea of Bond being played by a woman, with the sentiment echoed by Brosnan's Die Another Day costar, Halle Berry.

From BBC • Aug. 17, 2025

This past winter, "It Ends With Us" director and costar Justin Baldoni's team released a purported text from Lively in which she appeared to be flexing her powerful connections.

From Salon • Jun. 6, 2025

Second, the reconciliation and ensuing correspondence permitted Adams to join Jefferson as the costar of an artfully arranged final act in the revolutionary drama.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis