light-day

noun

: a unit of length in astronomy that is equal to the distance that light travels in one day in a vacuum or about 26 billion kilometers

The Ultimate Dictionary Awaits

Expand your vocabulary and dive deeper into language with Merriam-Webster Unabridged.

  1. Expanded definitions
  2. Detailed etymologies
  3. Advanced search tools
  4. All ad-free

Discover what makes Merriam-Webster Unabridged the essential choice for true word lovers.

Start Your Free Trial Now

Dictionary Entries Near light-day

light dawns

light-day

light displacement

See More Nearby Entries 

Cite this Entry

“Light-day.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/light-day. Accessed 22 Dec. 2024.

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 All

Point of View: It's Personal

Plural and Possessive Names: A Guide

What's the difference between 'fascism' and 'socialism'?

More Commonly Misspelled Words

Words You Always Have to Look Up
See All

Popular in Wordplay

See All

8 Words with Fascinating Histories

8 Words for Lesser-Known Musical Instruments

Birds Say the Darndest Things

10 Words from Taylor Swift Songs (Merriam's Version)

10 Scrabble Words Without Any Vowels
See All

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 Word Game 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
naughty or nice
Are you naughty or nice? Quiz He's making a quiz, and checking it twice...