“Only one or two would appear in a historical costume of very rich brocade, the hair most elaborately dressed with the ornaments peculiar to that particular period.”
“She had been wearing this invincible persona as a costume to hide her weakness.”
“Wear your normal costume for swimming and we'll dry this one off and you can wear it just for playing in.”
costumer
A person who designs, makes or supplies theatrical costumes; a costumier.
A person who wears a costume or takes part in cosplay.