cock ‧ sure /ˌkɒkˈʃʊə $ ˌkɑːkˈʃʊr/ BrE AmE adjective old-fashioned
[ Date: 1500-1600 ; Origin: cock word used to avoid saying 'God' (14-19 centuries) + sure ]
too confident of your abilities or knowledge, in a way that is annoying to other people:
He seemed rather too cocksure for my liking.