What is a theatrical try out called?

A theatrical tryout is most commonly called a preview performance or simply previews.

Here are some other terms that are sometimes used:

* Out-of-town tryout: This term is used when a show is trying out in a different city before its Broadway or West End opening.

* Workshop production: This term is used when a show is still in development and is being tested with an audience.

* Off-Broadway tryout: A show may have a tryout in a smaller venue before it opens on Broadway.

Ultimately, the specific term used will depend on the context and the specific stage of development the show is in.