The Collaborative International Dictionary of English v.0.48:

Entr'acte \En`tr'acte"\, n. [F. Cf. Interact.]
   1. The interval of time which occurs between the performance
      of any two acts of a drama.
      [1913 Webster]

   2. A dance, piece of music, or interlude, performed between
      two acts of a drama.
      [1913 Webster]