What is the meaning of "break a leg"?

The meaning of "break a leg" is:

good luck!

What is the definition of "break a leg"?

The definition of "break a leg" is:

good luck!

"break a leg" means

good luck!

Example Sentences:

A: I have a presentation to do today!
B: Break a leg! I hope it goes well!

The actor was told to break a leg as he prepared to go on stage.

From the News:

Break a leg, say gamblers, as Mills enters dance contest