evening dress

plural evening dresses

1. countableAn elegant dress worn by women, especially for social events in the evening, an evening gown.
2. uncountableFormal attire worn for evening social events.

   I felt uncomfortably conspicuous, since I was the only man in evening dress.

   1 more example

   She was frankly disappointed. For some reason she had expected to discover a burglar of one or another accepted type—either a dashing cracksman in full-blown evening dress, lithe, polished, pantherish, or a common yegg, a red-eyed, unshaven, burly brute in the rags and tatters of a tramp.

   1914 November, Louis Joseph Vance, “An Outsider […]”, in Munsey’s Magazine, volume LIII, number II, New York, N.Y.: The Frank A[ndrew] Munsey Company, […], published 1915, →OCLC, chapter III (Accessory After the Fact), page 382, column 2