If you needed your tonsils removed but your surgeon accidentally took out your appendix instead, you could sue her for malpractice, or mistreatment by a doctor that results in harm to the patient.
There are many kinds of malpractice, but medical and legal — by a doctor or lawyer — are the most common. Any professional who injures a client or patient through negligence risks being accused of malpractice, and possibly taken to court. The prefix mal means "bad," from the Latin word malus, or "evil." Practice comes from the Modern Latin practicare, "to practice." If a doctor practices medicine badly enough that it hurts someone, that's malpractice.
