Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

astronomical unit

noun

Definition of astronomical unit

  1. :  a unit of length used in astronomy equal to the mean distance of the earth from the sun or about 93 million miles (150 million kilometers)



1903

First Known Use of astronomical unit

1903


Learn More about astronomical unit


Seen and Heard

What made you want to look up astronomical unit? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

immature or lacking adult sophistication

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image567572573

Which of these is a synonym of unctuous?

maudlin angry oily prompt
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ