1.the attire worn in a play or at a fancy dress ball;
he won the prize for best costume
2.unusual or period attire not characteristic of or appropriate to the time and place;
in spite of the heat he insisted on his woolen costume
3.the prevalent fashion of dress (including accessories and hair style as well as garments)
4.the attire characteristic of a country or a time or a social class;
he wore his national costume
1.dress in a costume;
We dressed up for Halloween as pumpkins
2.furnish with costumes; as for a film or play