The term "onstage" usually refers to the fact that a performer or performer group is performing in front of an audience. When a performer is "onstage," they are in the center of the action.
She was backstage during the performance, and she was very nervous.
The singer was onstage the whole time, and she looked very uncomfortable.
ADV
situated or taking place on the area of a stage visible to the audience
ADV
on the stage
1
Initially he drank to allay the anxiety of going onstage.
2
Of props, however, there are many, lugged onstage by the five performers as the piece opens.
3
His authority onstage and his ingratiating manner made me very comfortable.
4
He's a pampered, miserable, abusive, sleazy, insecure wreck, toying with groupies and numbing himself before going onstage.
5
The wedding is in full swing onstage.
6
The woodcut shows Armin onstage.
7
He loved to entertain, onstage and off.
8
He once played a baboon onstage.
9
He runs onstage and vomits into a tuba.
10
She dies onstage, a martyr to virtue.