crazy [L16th] The root here is the verb to craze [LME], which is now ‘to drive mad, send crazy’ [E16th] or ‘to develop a network of small cracks’ [L19th] but originally meant ‘to break in pieces, shatter’. So a crazy person has had their sanity shattered. Crazy formerly meant ‘broken, damaged’ and ‘frail, unwell, infirm’. See also daft.