1.NounThe practising of something which is to be performed before an audience, usually to test or improve the interaction between several participating people, or to allow technical adjustments with respect to staging to be done.
2.NounA preparatory activity analogous to a rehearsal (sense 1).
"The forest fires are just a rehearsal for the devastation that will be caused if climate change continues to worsen."
3.NounThe act of rehearsing or contriving something; the fact of something's being rehearsed.
"The prosecution argued that the defendant's exact repetition of his account of the events several times demonstrated the rehearsal of his story."