costume vs overdress

costume is a noun but overdress is not a noun.

Word	Noun	Adjective	Verb	Adverb
costume	Yes	No	Yes	No
overdress	No	No	Yes	No

costume (noun)	overdress (noun)
the attire worn in a play or at a fancy dress ball
the attire characteristic of a country or a time or a social class
unusual or period attire not characteristic of or appropriate to the time and place
the prevalent fashion of dress (including accessories and hair style as well as garments)

costume (verb)	overdress (verb)
dress in a costume	put on special clothes to appear particularly appealing and attractive
furnish with costumes; as for a film or play	dress too warmly