speed of light
noun phraseDefinition of speed of light
: a fundamental physical constant that is the speed at which electromagnetic radiation propagates in a vacuum and that has a value fixed by international convention of 299,792,458 meters per second
—symbol c
Learn More About speed of light
Statistics for speed of light
Look-up Popularity
Cite this Entry
“Speed of light.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/speed%20of%20light. Accessed 19 Jan. 2022.
Style: MLA
MLA
Chicago
APA
Merriam-Webster
Chicago
APA
Merriam-Webster
Test Your Vocabulary
Difficult Spelling Words Quiz
-
- Which is the correct spelling?
Can you spell these 10 commonly misspelled words?
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Share speed of light
Time Traveler for speed of light
The first known use of speed of light was in 1823
See more words from the same year