An unusual or amusing costume worn to a social event to make someone look like, for example, a famous person or well-known fictional character.
‘schoolchildren were in the procession in fancy dress’
‘a fancy dress competition’
‘Then of course there is the famous fancy-dress competition in which everyone who has arrived in costume is invited onto the stage to show off.’
‘The costume party is formatted as a multi-venue themed fancy-dress art party and is attended by 8000 thousand partygoers - who arrive in teams in matching costumes - somehow related to the theme.’
‘They talk of going to future fancy-dress parties and of the costumes worn there.’
‘Don't bother hiring an expensive fancy-dress costume.’
‘Following this is a fancy-dress competition, in which everyone in a Von Trapp costume will be invited on stage.’