0 a party where people wear special clothes that make them look like a particular character, animal or object:
He was seen in 18th century garb at costume parties and other social gatherings.
The boys return home, explain to their father everything they saw at the bank and during the chase, and then head out to the costume party.
She made an elaborate diamond-encrusted space suit for the convention's costume party, which started her thinking about what sort of character would wear such a suit.
It takes place at a costume party being held in a mansion.
She later attends a costume party with the people.
Guests at a costume party or a fancy dress party wear costumes.
Four years later, they celebrate the birthday of their twin daughters with a costume party.
Ballard himself makes a cameo appearance at the costume party scene.