Define criminal. criminal synonyms, criminal pronunciation, criminal translation, English dictionary definition of criminal. adj. 1. Of, involving, or having the nature of crime: criminal abuse.
CRIMINAL definition: 1. someone who commits a crime: 2. relating to crime: 3. very bad or morally wrong: . Learn more.
A criminal is someone who breaks the law. If you're a murderer, thief, or tax cheat, you're a criminal.
CRIMINAL definition: of the nature of or involving crime. See examples of criminal used in a sentence.