(all) dressed up

(all) dressed up

Dressed formally, perhaps more formally than usual. You need to be dressed up for this event tonight—a suit and tie is appropriate. Because I was all dressed up for the birthday party, I was embarrassed when I saw that the other guests were in shorts and T-shirts.
See also: dress, up
Farlex Dictionary of Idioms.

*(all) dressed up

dressed in one's best clothes; dressed formally. (*Typically: be ~; get ~; get someone ~.) I really hate to get all dressed up just to go somewhere to eat.
See also: dress, up
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • dressed up
  • dress up
  • dressed to kill
  • dressed to the teeth
  • dressed to the nines
  • 9s
  • be dressed (up) to the nines
  • dressed (up) like a dog's dinner
  • dressed like a dog's dinner
  • dressed up like a dog's dinner