cocksure

American  

[kok-shoor, -shur] / ˈkɒkˈʃʊər, -ˈʃɜr /

adjective

1. perfectly sure or certain; completely confident in one's own mind.

   She was cocksure that she was able to do the job better than anyone else.

   Synonyms:

   conceited, arrogant, cocky

2. too certain; overconfident.

   He was so cocksure he would win the election that he didn't even bother to campaign.

3. Obsolete. perfectly secure or safe.

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cocksure British  

/ ˌkɒkˈʃʊə, -ˈʃɔː /

adjective

1. overconfident; arrogant

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Other Word Forms

• cocksurely adverb
• cocksureness noun

Etymology

Origin of cocksure

First recorded in 1510–20; cock ¹ + sure

Example Sentences

“I wish I was as cocksure of anything as Tom Macaulay is of everything.”

From The Wall Street Journal • Mar. 30, 2026

And it became famous for Ingle's unconventional training methods which allowed his boxers to become flamboyant and cocksure with fancy footwork.

From BBC • Jan. 9, 2026

Back at the attorney’s office, I watched Gray’s family and lawyers all moved to tears by Mosby’s words—even famously cocksure defense attorney Billy Murphy!—and her audacious attempt to hold Baltimore police accountable for Gray’s death.

From Slate • May 24, 2024

In January, the cocksure governor told Times reporter Taryn Luna in an interview: “I think it’s going to win overwhelmingly. Period. Full stop.”

From Los Angeles Times • Mar. 13, 2024

The moment we walked out of the classroom, his cocksure veneer, the spit and polish, would return.

From "We Are the Ants" by Shaun David Hutchinson