cocksure

adj

1. (informal)Too confident; overconfident.

   “I thought myself cocksure of his horse, which he readily promis'd me.”

   “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.”

   “These crack specialists, the young scientific fellows, they're so cocksure and so wrapped up in their laboratories that they miss the human element.”