Iapetus

noun

Iap·​e·​tus ī-ˈa-pə-təs How to pronounce Iapetus (audio)
astronomy
: the third largest satellite of Saturn with a diameter of approximately 890 miles (1440 km)
Ever since J.D. Cassini discovered the object in 1671, astronomers have puzzled over why Iapetus' leading hemisphere (facing forward along its orbit) is dark and its trailing one bright.—J. Kelly Beatty, Sky & Telescope, November 1983

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!

Dictionary Entries Near Iapetus

IAP

Iapetus

Iapygian

See More Nearby Entries 

Cite this Entry

“Iapetus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Iapetus. Accessed 1 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

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)

Plural and Possessive Names: A Guide

The Difference Between 'i.e.' and 'e.g.'

Why is '-ed' sometimes pronounced at the end of a word?

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

Popular in Wordplay

See All

Terroir, Oenophile, & Magnum: Ten Words About Wine

8 Words for Lesser-Known Musical Instruments

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

9 Superb Owl Words

15 Words That Used to Mean Something Different
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
sweet smart pug puppy dog sitting in front of blackboard with chalk question marks
Commonly Confused Words Quiz Vol. 3 Do you have a (flare/flair) for choosing the righ...