know-it-all

American

[noh-it-awl] / ˈnoʊ ɪtˌɔl /

noun

a person who acts as though they know everything and who dismisses the opinions, comments, or suggestions of others.

adjective

of or characteristic of a person who acts as though they know everything and who dismisses the opinions, comments, or suggestions of others.

know it all Idioms

see know all the answers.

Etymology

Origin of know-it-all

First recorded in 1930–35

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

We want to know it all, to see every vision of the next life and spend our lives doing whatever we can to get there.

From Salon • Nov. 27, 2025

A voyager is curious and open to the idea that they don’t know it all.

From Slate • Jan. 14, 2024

But members of the secondary know it all starts up front with the defensive line.

From Seattle Times • Aug. 31, 2023

Virgos are like, “I know it all even if I’m wrong.”

From Los Angeles Times • Jun. 23, 2023

It’s weird: This whole time I had been thinking about Auggie like he was my enemy, but when Grandmère told me that story, I don’t know, it all kind of just sank in with me.

From "Auggie & Me" by R. J. Palacio

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023