I remember seeing a word that has the same meaning as aside - something that a character in a play says to the audience, but which the other characters on stage are not intended to hear - perhaps longer than this one. But I don’t find it on synonym dictionaries. Is it my illusion that I saw it?
1. The conventional whisper of an actor, intended to be heard by the audience but supposedly inaudible to others on stage.
The meaning is not exactly the same but have you looked at "soliloquy"?