Definition of insanity noun from the Oxford Advanced American Dictionary
insanity
noun
/ɪnˈsænət̮i/
[uncountable]
1the state of being insaneHe was found not guilty, by reason of insanity.antonymsanity2actions that are very stupid and possibly dangeroussynonymmadness, lunacyIt would be sheer insanity to attempt the trip in such bad weather.