From Longman Dictionary of Contemporary Englishmorning suitˈmorning suit noun [countable] DCCa man’s suit that is worn at formal ceremonies during the day, especially weddings
Examples from the Corpus
morning suit• On the morning she saw him standing in the body of the church, dark as a gypsy in his morning suit.• He was dressed in a Victorian morning suit, high starched collar, watered-silk cravat. 