cocksure

The word "cocksure" paints a vivid picture of excessive self-confidence, inspired by the image of a rooster (a “cock”) strutting around as if it can’t possibly be wrong. It’s more than simple self-belief: it suggests an unwarranted, often irritating level of certainty—especially when the facts don’t actually support it.

In everyday English, "cocksure" usually means brashly certain. The person doesn’t just think they’re right; they act like there’s nothing to discuss. That’s why it often carries a negative tone: it hints at arrogance, a lack of humility, and an unwillingness to consider other perspectives.

You might say someone is “cocksure about their predictions,” meaning they speak with total confidence about how things will turn out, even if they don’t have much evidence. A cocksure attitude can be off-putting—and risky—because it can lead someone to ignore warnings, dismiss advice, or charge ahead without checking their assumptions.

Confidence is generally admired, but cocksure confidence feels inflated. It’s the difference between “I’ve prepared, so I think this will work” and “This will work, end of story.” If someone seems overly certain of themselves, especially when they shouldn’t be, they might be cocksure.