A state of mental illness or extreme folly.

Extreme foolishness or irrationality in behavior.

व्यवहार में चरम मूर्खता या असंगतता।

English Usage: It was sheer insanity to invest all his savings in that failing business.

Hindi Usage: उस असफल व्यवसाय में अपनी सारी जमा पूंजी लगाना पूरी मूर्खता थी।