To prosecute means to formally accuse someone of a crime and bring them to trial in court. When the government prosecutes a case, lawyers called prosecutors present evidence to prove that the accused person broke the law. If you've watched courtroom dramas, the prosecutor is the lawyer arguing that the defendant is guilty.

District attorneys and their assistants prosecute criminal cases on behalf of the community, while defense attorneys represent the accused person.

Prosecution is different from persecution, though the words sound similar. Persecution means unfairly attacking or harming people, often because of their beliefs or identity. Prosecution means following proper legal procedures to determine if someone broke the law.

The word can also mean to carry something through to completion with determination. A general might prosecute a military campaign, or a scientist might prosecute her research on a difficult problem. In this sense, it means pursuing something persistently and thoroughly until you achieve your goal.