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.

---

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

The result: As of last quarter, the number of new apartments under construction in San Diego County rose 10% from three years earlier, CoStar data show.

From Los Angeles Times

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

Occupancy at area hotels was down 5.6% between November 2024 and November 2025, according to data company CoStar.

From The Wall Street Journal

CoStar Group plans to reduce its net investment in Homes.com by over $300 million in 2026 from $850 million in 2025.

From Barron's

CoStar expects 2026 revenue between $3.78 billion and $3.82 billion, an 18% increase from prior 2025 guidance.

From Barron's