black-tie

adjective

1. requiring that guests wear semiformal attire, especially that men wear black bow ties with tuxedos or dinner jackets: a black-tie dance.

noun

1. a black bow tie, worn with a dinner jacket.
2. semiformal evening wear for men (distinguished from white tie).

noun

1. a black bow tie worn with a dinner jacket
2. (modifier) denoting an occasion when a dinner jacket should be worn