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

Here he is displaying all these qualities in a concentrated burst of glib, cocksure simplemindedness during a July 19, 2022, appearance on C-SPAN:

From Los Angeles Times • Oct. 27, 2023

He had a gift for sleeping, he’d boasted, smiling in that cocksure way of his.

From "A Dance with Dragons" by George R. R. Martin