The idiom “break a leg” means “good luck” and is most famously used in the theater world. Wishing someone good luck directly was once believed to bring bad luck, so performers began saying the opposite to avoid jinxing a performance.
One leading theory traces its origin to the “leg lines,” or side curtains, on stage. In early vaudeville, where performers took turns entertaining the audience, standby acts were only paid if they actually went on stage, literally crossing the “leg line.”
Thus, to tell someone to “break a leg” meant wishing them success and a chance to perform (and get paid). Today, the phrase has transcended theater and is used before any big event or performance. For example: “Break a leg on your presentation!” or “She told her son to break a leg before his audition.”
