What it means

1. adjective of the back half of a stage
   “she crossed to the upstage chair forcing the lead to turn his back to the audience”
2. adjective remote in manner
   “stood apart with aloof dignity”
3. noun the rear part of the stage
4. adverb at or toward the rear of the stage
   “the dancers were directed to move upstage”
5. verb steal the show, draw attention to oneself away from someone else
   “When the dog entered the stage, he upstaged the actress”
6. verb move upstage, forcing the other actors to turn away from the audience
7. verb treat snobbishly, put in one's place