Definitions of criminal:

• noun:   someone who has committed (or been legally convicted of) a crime
• adjective:   guilty of crime or serious offense

  Example: "Criminal in the sight of God and man"

• adjective:   involving or being or having the nature of a crime

  Example: "A criminal offense"

• adjective:   relating to crime or its punishment

  Example: "Criminal court"

• adjective:   bringing or deserving severe rebuke or censure

  Example: "A criminal waste of talent"