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 Poehler had her friend and “Parks” costar Aubrey Plaza on the show last August, Poehler very softly asked Plaza how she was doing since her husband, Jeff Baena, died eight months earlier.

From Salon • Jan. 16, 2026

“Well, it’s Ken Watanabe; he has that aura, that presence that was overwhelming,” star Kento Yamazaki told Salon about his costar in the pivotal scene.

From Salon • Sep. 29, 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

"Don't you think it's kind of awesome to be, like, the costar of Tiny's life?"

From "Will Grayson, Will Grayson" by John Green and David Levithan