Comprehensive resource for understanding and mastering English idioms
The idiom "break a leg" is commonly used to wish someone good luck, usually before a performance. It can also be used more casually as a way of expressing excitement or enthusiasm for something upcoming. The phrase doesn't mean that the person should literally break their legs, but rather that they should have a great time and perform well.
The origin of the phrase "break a leg" is unclear, but it has been used in the theater world since at least the 19th century. It may have come from the tradition of bending one's knee (or "breaking" one's leg) as a sign of respect or deference. Another theory suggests that it comes from the idea that performers should strive to give their best performance, and if they do, they will break a leg (meaning receive applause). The idiom has also been used outside of the theater world in recent years, particularly in regards to events such as concerts or sports matches.