Is “Costar” a Scrabble word?
Yes
COSTAR
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Costar
noun
1.A person who shares star billing
“The once famous actor objected to his costar having a bigger dressing room.”
2.A person who slightly lacks the status to be considered a star
“Alas, always a costar but never a star.”
verb
1.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.”