light–day

noun

Definition of light–day

  1. :  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

There's more!

Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!
Already a subscriber? Log in.

Seen and Heard

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

Love words? Need even more definitions?

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

WORD OF THE DAY

the point at which something begins

Get Word of the Day daily email!

Love words? Need even more definitions?

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