In a theater, when the houselights dim or go down, the lights where the audience sits are switched off. When thehouselights come up, the lights are switched on.
houselights in American English
(ˈhaʊsˌlaɪts)
plural noun
the lights that illuminate the part of a theater where the audience is seated
Examples of 'houselights' in a sentence
houselights
Then he says he wants the houselights up so he can see the audience, now we've seen him.