The Definition of Instanity!

in·san·i·ty / inˈsanitē/  noun: insanity

1. the state of being seriously mentally ill; madness. "he suffered from bouts of insanity" synonyms: mental illness, madness, dementia; 

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

4. doing the same thing over and over again and expecting different results. (Albert Einstein)