insanity
/ɪnˈsanəti/
noun
the state of being seriously mentally ill; madness.
"he suffered from bouts of insanity"
Similar:
mental illness, mental disorder, mental derangement, madness
extreme foolishness or irrationality.
plural noun: insanities
"it would be pure insanity to race over 1950m or 2000m at Nelson"