First recorded in 1930–35
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Sandwiched between his rebellious older brother, Dylan, and his know-it-all younger brother, Miles, Felix finds it easier to ignore the world around him.
From The Wall Street Journal • Jun. 12, 2026
In a 2015 biography, author Ashlee Vance described Musk as "a confrontational know-it-all" with an "abundant ego".
From BBC • Jun. 4, 2026
Volker Beck, president of the German-Israeli Society, labelled Steinmeier's comments on the war "grossly inappropriate" and said they displayed a "smug know-it-all attitude".
From Barron's • Mar. 24, 2026
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.
From Los Angeles Times • Sep. 20, 2025
Roland Mathers, who is kind of a know-it-all and talks like he’s forty, raises his hand and starts to speak even before she calls on him.
From "Finding Junie Kim" by Ellen Oh
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
