1. Relating to being involved in an illegal activity or activities: "The psychologists were understand how the criminal mind functions."

"The captain of the wrecked cruise ship has been accused of criminal negligence."

2. A reference to laws which describe crimes instead of those legal acts about a person's rights: "The local criminal justice-system has been accused of mishandling the charges brought against the mayor of the city."
3. Morally wrong: "Many are convinced that it is criminal that congress and the president are doing nothing to stop the shut down of the government!"