1. A condition in which a person suffers a wrong or is under some hardship, esp. one that a statute seeks to remove or for which equity provides a remedy (this legislation seeks to eliminate the mischief of racially restrictive deed covenants).
2. Injury or damage caused by a specific person or thing (the vandals were convicted of criminal mischief).
3. The act causing such injury or damage (their mischief damaged the abbey).