Neatorama presents a guest post from actor, comedian, and voiceover artist Eddie Deezen. Visit Eddie at his website.

The term "break a leg" is unique to actors. Actors often tell each other to "break a leg" and the term is also commonly used by non-actors, who wish the sentiment on actual actors. It means, of course, "Do well!" or "Have a great show!" The term can be used before a stage performance, a show, or an audition. I have never heard it used before filming a movie, but I guess it can be used on that occasion, too.

Interestingly, stagehands do not use the term, just actors. Stagehands will often tell each other "Don't mess up" or the more graphic "Don't f*** up" before a big or important performance.

Like many popular sayings and terms, the origin of "break a leg" is nebulous and disputed. The term "break a leg" was used originally, some say, to discourage evil spirits from deliberately causing one's performance to suffer. According to this theory, wishing someone "good luck" would be invoking the "evil eye." So "good luck" would actually cause bad luck for the actor. This, "break a leg," by this logic, would be a wish for good luck.

The term "break a leg" may be traced back to the Elizabethan language. To "break a leg" in Shakespeare's time meant, literally, to bow -by bending at the knee. Since a successful actor would "break a leg" onstage and receive applause, the phrase would, in effect, be a wish for good luck. However, in the 16th century "break a leg" also meant to give birth to an illegitimate child, which is hard to connect to the theatrical world.