Definitions

1. verb

to appear in a film or television show with another actor

“She costarred with Tom Hanks in the blockbuster movie.”

2. verb

to have the same star or celestial body as another place or event

“The two constellations costarred in the night sky.”

3. noun

a celebrity who appears in a film or television show with another actor

“The costar of the movie won several awards for their performance.”

4. noun

a celestial body that appears with another in the night sky

“The two planets costarred in the morning sky.”