offstage

nouns

a stage area out of sight of the audience

adjectives

situated or taking place in the area of a stage not visible to the audience
"offstage noises"
antonym
concealed from public view or attention
"offstage political meetings"

adverbs

behind the scenes; not on stage
"the actors were waiting offstage"
antonym
not in public
"the deal was done offstage"