know-it-all

[noh-it-awl]

noun

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

adjective

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

Word History and Origins

Origin of know-it-all¹

First recorded in 1930–35

Idioms and Phrases

see know all the answers.

Example Sentences

Soft know-it-alls from the city and phonies of any stripe receive rough treatment in his shows, such as the llama farmer from California who gets thrown under a Montana cattle guard in “Yellowstone.”

Read more on The Wall Street Journal

The idea was to put to rest any worry that she might parade in like a know-it-all.

Read more on The Wall Street Journal

I have been a know-it-all Dodger fan since the late 1950s and after last season I thought, and hoped, Clayton Kershaw would retire.

Read more on Los Angeles Times

He could come off as a know-it-all, and he tended to ramble when speaking.

Read more on Salon

Of course, being a kid is full of trial and error, especially when you’re a know-it-all.

Read more on Salon

Related Words

• smart aleck 
• wise guy