What is the meaning of Costar?

A person who shares star billing with another.

A person who slightly lacks the status to be considered a star.

To perform with the billing of a costar.

To feature (a number of star performers) jointly.

to cost (incur a charge, a price)

to cost (have a given price)

to be very difficult

to cost

to cost

to find something very difficult, to have a hard time with something

to cost

Source: wiktionary.org