sitzprobe
The first run-through of an opera or musical in which the orchestra and singers rehearse together, covering only those portions of the piece in which the orchestra plays, and in which the singers sit or stand at microphones, but do not block out any action.
However, something happens with almost every musical that puts the cast on edge, when the cast takes the stage for the sitzprobe or wandelprobe.
Where it comes from
Borrowed from German Sitzprobe (“seated rehearsal”). From sitz + probe.
Adapted from the Wiktionary entry sitzprobe (CC BY-SA 4.0).