original definition was the theatrical intermission, now it more commonly refers to the music performed during the intermission
► uses
Uses:
A celebrated singer was singing for the second time, and all the fashionable world was in the theater. Vronsky, seeing his cousin from his stall in the front row, did not wait till the entr'acte, but went to her box.
Leo Tolstoy. Anna Karenina (Translated by Constance Garnett)
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DURING THE entr’acte a whiff of cold air came into Helene’s box, the door opened, and Anatole entered, stooping and trying not to brush against anyone.