A term made by Brad Taste In Music (a music critique youtuber) to describe dramatic, over-the-top songs reminiscent of Broadway Theatre. Prime examples include Miracle Musical and Panic! At The Disco.
A: "Hey, have you ever heard Hawaii Part II? It's such an amazingexperience!"
B: "Nah man, it's way too theatrecore to me."
The overwhelming sadness that you get after the play/musical you were in closes. It is very hard to treat, as it is unlikely you will ever do that play/musical again.
Jim: Hey, what have you been doing since the show ended?
Joe: Not much, I've been dealing with a pretty bad case of theatrical depression. I haven't left the house in two weeks.