costume worn at masquerades, etc, usually representing a particular role, historical figure, etc (as modifier): a fancy-dress ball
WordReference Random House Unabridged Dictionary of American English © 2025
fan′cy dress′,
- Clothinga costume for a ball, masquerade, etc., chosen to please the fancy, usually a costume characteristic of a particular period or place, class of persons, or historical or fictitious character.
- 1760–70
Collins Concise English Dictionary © HarperCollins Publishers::
'fancy dress' also found in these entries (note: many are not synonyms or translations):