fancy dress noun
[noncount] chiefly Brit : special clothes that you wear to a party where people are dressed to look like famous people, characters, etc.
▪ Everyone wore fancy dress for the ball. ▪ a fancy-dress ball/party [=a costume ball/party]
▪ Everyone wore fancy dress for the ball. ▪ a fancy-dress ball/party [=a costume ball/party]
