[in.san.i.ty] n, pl -ties (1590) 1 a: a deranged state of the mind usu. occurring as a specific disorder (as schizophrenia) and usu. excluding such states as mental retardation, psychoneurosis, and various character disorders b: a mental disorder
2: 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 a: extreme folly or unreasonableness b: something utterly foolish or unreasonable