Origin of costarco- + star
tr. & intr.v.co·starred, co·star·ring, co·stars also co-starred or co-star·ring or co-stars
- (acting) A person who shares star billing.
- The once famous actor objected to his costar having a bigger dressing room.
- (acting) A person who slightly lacks the status to be considered a star.
- Alas, always a costar but never a star.
(third-person singular simple present costars, present participle costarring, simple past and past participle costarred)
- to perform with the billing of a costar.
- People thought his career was over but now he will get to costar on Broadway next month.
co- + star