What theatrical term means a rehearsal without performers?

A dry tech rehearsal. A technical rehearsal is done without actors or props so the technical crew with lighting and special effects can get their timing down for the performance. A sound check is usually done after the lighting along with any mechanics of moving props on and off the stage or any mechanical features that are part of the performance.

https://en.wikipedia.org/wiki/Technical_rehearsal

There is also a closed rehearsal only open to a few performers who are directly involved for sensitive areas like sex scenes.

https://www.theatrefolk.com/blog/rehearsals-need-include-schedule-may-not-thought