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

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

"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