Iapetus

noun
Iap·​e·​tus | \ī-ˈa-pə-təs \

Definition of Iapetus 

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!

Learn More about Iapetus

Dictionary Entries near Iapetus

ianthinite

iao

IAP

Iapetus

Iapygian

Iapygidae

iarovize

Statistics for Iapetus

Look-up Popularity

Comments on Iapetus

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

WORD OF THE DAY

noxious or harmful

Get Word of the Day daily email!

Test Your Vocabulary

A Thanksgiving Word Quiz

  • a-traditional-thanksgiving-dinner
  • November comes from a word for which of the following numbers?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
Word Winder's CrossWinder

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

TAKE THE QUIZ

Love words? Need even more definitions?

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