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1 definition by Ben Whitehouse

Rainbow formal is a dress code similar to black tie, where the attendees to the event (normally a ball or awards ceremony) are required to not wear the usual white shirt, with black tie, jacket and trousers and instead wear more colourful attire.
"We organised an event and eschewed the usual black tie formal and went for Rainbow Formal"
by Ben Whitehouse May 02, 2006