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.
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 theatricaldepression. I haven't left the house in two weeks.
Often overdramatized behavior verbal and/or non-verbal to accentuate a point or display an emotion. It differs from theater or drama because it's more comprehensive including real life situations and people. Theatrics can run the full range of human emotion and expression from humorous to very serious depending on the context of the situation. Melodrama and is often accompanied with it but not in every case. Theatrics can have extreme physical movement to express an emotion or idea but, also, not in every case. Theatrics can be very subtle as well.
"Did you see that skater kid's theatrics after he fell on his ass?"
"Well sir, I've had enough of your maniacal theatrics...they're disruptive to this classroom and this institution!"
"The theatrics of the very first Saturday Night Live group were subtle, colorful and well-timed making some of their skits some of the best televised comedy of all-time.