Definitions for "Dress rehearsal"
The final rehearsal of a play prior to its first live performance. All actors are in full costume and and all props in place, the play being performed exactly as the audience will see it.
a rehearsal in costume and makeup, with full props, scenery, and lighting, ideally without interruptions; the conductor is at the podium and the director and designers in the house. There are two types of opera dress rehearsals: piano and orchestra (q.v.)
The final rehearsal, using all of the costumes, lights, etc.. While sometimes it is necessary to stop for corrections, an attempt is made to make it as much like a final performance as possible.
simulation of a conversion event under realistic conditions so that issues can be identified and resolved prior to live implementation.