you don't know

idiom

Definition of you don't know 

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

Learn More about you don't know

Share you don't know

Comments on you don't know

What made you want to look up you don't know? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

not any or not one

Get Word of the Day daily email!

Test Your Vocabulary

Great Scrabble Words—A Quiz

  • scrabble-tiles-that-read-scrabble-quiz
  • Which of the following Q-without-U words means the number five in cards or dice?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

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