From Longman Dictionary of Contemporary Englishlunacylu‧na‧cy /ˈluːnəsi/ noun [uncountable] 1 CRAZYa situation or behaviour that is completely crazy SYN madness It would be sheer lunacy to turn down a job offer like that.2 old-fashionedMIMENTALLY ILL mental illness
Examples from the Corpus
lunacy• In drunken lunacy we had two execrable hamburgers and three orders of cold, greasy fries at the refreshment stand.• The signs of inherent lunacy have always been there.• But assisting her investigations into a perfectly natural death as if it were murder was little short of lunacy.• This sort of lunacy goes on every day in the public schools and universities of our nation.• To administer torture while within the warp - to a talented Astropath of all people - would be plain lunacy.• Does he agree that such a policy - it is, of course, Labour policy - would be sheer lunacy?• It seemed an act of sheer lunacy.sheer lunacy• And fans are in no doubt as to where bravery ends and sheer lunacy begins.• In these conditions, to encourage mass protest over which they would have no control appeared sheer lunacy.• It would be sheer lunacy to turn down a great offer like that.• Does he agree that such a policy - it is, of course, Labour policy - would be sheer lunacy?• It seemed an act of sheer lunacy.Origin lunacy (1500-1600) lunatic 