criminal /ˈkɹɪm.ɪ.nəl/noun 1adjective 4forms 3 noun1 •a person who has done something against the law, such as stealing or killing adjective4 •Against the law; forbidden by law.Foppish and fantastic ornaments are only indications of vice, not criminal in themselves. — 1711 •Of or relating to crime or penal law.His long criminal record suggests that he is a dangerous man. •Guilty of breaking the law.The neglect of any of the relative duties renders us criminal in the sight of God. — 1729 •(figurative) Abhorrent or very undesirable.Printing such asinine opinions is criminal! formscriminals · more criminal · most criminal