Traitionally, insanity or madness is the behaviour whereby a person flouts societal norms and becomes a danger to himself and others. Greek tragedies and Shakespeare often refer to madness in this sense. Psychologically, it is a general popular and legal term defining behaviour influenced by mental instability. It is defined by the Merriam-Webster dictionary as a deranged state of the mind or lack of understanding. Today, it is most commonly encountered as an informal term or in the narrow legal context of the insanity defense, and in the medical profession the term is now avoided in favour of specific diagnoses of mental illness as schizophrenia and other psychotic disorders. When discussing mental illness in general terms, "psychopathology" is also considered a preferred descriptor.