know-it-all

[ noh-it-awl ]
/ ˈnoʊ ɪtˌɔl /

noun

a person who acts as though he or she knows everything and who dismisses the opinions, comments, or suggestions of others.

adjective

of or characteristic of a know-it-all.

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Origin of know-it-all

First recorded in 1930–35
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Idioms and Phrases with know it all

know it all

see know all the answers.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.