Cocksure means far too sure of yourself. A cocksure young man, cocksure and wrong, insufferably cocksure.
It is always a criticism, and the charge is certainty out of proportion to knowledge rather than confidence as such. It is old-fashioned. Note that the word originally meant perfectly secure, with no disapproval in it at all, and that the cock in it may be the cock of a firearm or a tap.
1adjectivecocksureFar too sure of yourself.
“He was so cocksure before the exam that he didn't bother to revise, and he failed.”
synonyms: overconfident, brash
cocksure is a quality of overconfidence.
Cock plus sure, from the early sixteenth century. It first meant perfectly secure, and the cock may be that of a firearm or a tap.
Probably from cock + sure, early 16
Etymology from Wiktionary, CC BY-SA
Practised in A Song of Ice and Fire