cocksure
From Longman Dictionary of Contemporary Englishcocksurecock‧sure /ˌkɒkˈʃʊə $ ˌkɑːkˈʃʊr/ adjective old-fashioned CONFIDENTtoo confident of your abilities or knowledge, in a way that is annoying to other people He seemed rather too cocksure for my liking.Examples from the Corpuscocksure• She sounds confident, but not cocksure.• Berton was a powerful personality, a cocksure businessman with a fast-talking line in hard sell.Origin cocksure (1500-1600) cock word used to avoid saying “God” ((14-19 centuries)) + sure