(informal) too confident; overconfidentI thought myself cocksure of the horse which he readily promised me. — Alexander Pope.
1906, John Galsworthy, ,The persistence of the Past is one of those tragicomic blessings which each new age denies, coming cocksure on to the stage to mouth its claim to a perfect novelty.
1920, Sinclair Lewis, The Main Street,These crack specialists, the young scientific fellows, they're so cocksure and so wrapped up in their laboratories that they miss the human element.
