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

They misquoted him to his face, misrepresented his work, and spouted cocksure inanities showing with every word that, scientifically speaking, they have no idea what they’re talking about.

From Los Angeles Times • May 2, 2024

As his banishment gets closer, he only grows more cocksure.

From Slate • Nov. 16, 2023

Peter would be proud of me, I thought as I worked—and was flooded by a wave of lonesomeness for that brave and cocksure boy.

From "The Hiding Place" by Corrie ten Boom