Be dressed up Definition 1 of 4Pro Tip 1/3Event Specific Use 'be dressed up' for specific occasions where formal attire is expected or customary. Everyone was dressed up for the gala dinner. Pro Tip 2/3Not Always Formal It can also mean wearing something more fancy than usual, not just black-tie formal. They were all dressed up in their Sunday best. Pro Tip 3/3Positive Connotation 'Be dressed up' often implies effort put into appearance and can be a compliment. You're dressed up today—you look great!