co-star

• POS: Noun, Verb (usu participle)

CIDE DICTIONARY

co-star, v. t. 

 to feature as the co-star in a performance; as, the film co-starred Robin Williams as the psychiatrist.  [WordNet 1.5]

co-star, v. i. 

 to be the co-star in a performance; as, Robin Williams co-starred in the film.  [WordNet 1.5]

OXFORD DICTIONARY

co-star, n. & v.
--n. a cinema or stage star appearing with another or others of equal importance.
--v. (-starred, -starring)
1 intr. take part as a co-star.
2 tr. (of a production) include as a co-star.