Meaning of INSANITY in English

INSANITY

noun (plural -ties) Date: 1590 a deranged state of the mind usually occurring as a specific disorder (as schizophrenia), such unsoundness of mind or lack of understanding as prevents one from having the mental capacity required by law to enter into a particular relationship, status, or transaction or as removes one from criminal or civil responsibility, 3. extreme folly or unreasonableness, something utterly foolish or unreasonable

Merriam Webster. Explanatory English dictionary Merriam Webster.      Толковый словарь английского языка Мерриам-Уэбстер.