you don't know

idiom

—used for emphasis
You don't know how happy I am to see you.

Browse Nearby Words

you couldn't pay someone
you don't know
you don't say
See all Nearby Words

Cite this Entry

“You don't know.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/you%20don%27t%20know. Accessed 2 Jul. 2025.

Copy Citation

Share

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

More Words You Always Have to Look Up

Using Bullet Points ( • )

Should that word have a hyphen?

Words You Always Have to Look Up

Democracy or Republic: What's the difference?
See More

Popular in Wordplay

See More

How 'Namaste' Entered The English Language

12 Lovely and Unusual Words for the Natural World

10 Hella Good U.S. Regionalisms

Better Ways to Say 'This Sucks'

8 Words with Fascinating Histories
See More

Popular

See More

More Words You Always Have to Look Up

How 'Namaste' Entered The English Language

12 Lovely and Unusual Words for the Natural World
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
illustration of alice and tweedledee and tweedledum
Guess the Literary Image We show you the art, you guess the literary work....
See All