A run-through is a short practice of the whole thing before the real performance, test, or talk. You go from start to finish once, so everyone can see the shape of it — not yet the true show. In a theatre it is a rehearsal without the full costumes and lights; a dress rehearsal is a step more serious. A teacher may say, “We’ll do a run-through of the exam,” meaning you try the whole paper once so nothing feels new on the day. In an office people do a run-through of a presentation: they click the slides and say their lines out loud. It names a planned session, a bit more than a casual “let’s practise.” Though actually, in daily speech many people just say “Let’s go through it once.” You will still hear run-through a lot in theatre, events, and work. The hyphen is usual in writing: run-through. This is the noun. The verb run through has other lives (to go through something, or, in stories, to pierce someone with a sword); do not pour those into this one.