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

Actress Blake Lively has reportedly told a New York court that she lost more than $40 million as a result of “reputational damage” she suffered during her ongoing feud with her former costar, Justin Baldoni.

From MarketWatch • Apr. 30, 2026

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

For while other actors were as photogenic on screen as Dean, including “Giant” costar Elizabeth Taylor, it’s difficult to think of another star who made such an impact with his still images.

From Los Angeles Times • Sep. 30, 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

He could throw a tantrum or two until Jenny figured out what he wanted: Cha-Cha to costar in every episode!

From "Dog Squad" by Chris Grabenstein