Morning dress, also known as formal day dress, is the formal Western dress code for day attire, consisting chiefly of, for men, a morning coat, waistcoat, and formal trousers, and an appropriate gown for women. Men may also wear a popular variant where all parts (morning coat, waistcoat and trousers) are the same colour and material, often grey and usually called "morning suit" or "morning grey" to distinguish it; considered properly appropriate only to festive functions such as summer weddings and horse races, which consequently makes it slightly less formal. The correct hat would be a formal top hat, or if on less spacious audience settings optionally a collapsible equivalent opera hat.
Debrett's states that morning dress should not be specified as the dress code for events starting after 6 p.m. If a formal event will commence at or after 6 p.m., white tie should be specified instead. The semi-formal daytime counterpart of this code is the black lounge suit.
Morning dress is generally restricted to certain weddings, royal, governmental or municipal audiences, and social season events, e.g., horse races. It may also be seen sometimes worn at church services, as well as fraternal orders, and gentlemen's clubs.