Definition of Umbriel
: the third largest satellite of Uranus with a diameter of approximately 730 miles (1170 km) Earlier this year, Buratti and her co-workers reported other evidence suggesting that Umbriel might be a Uranian oddity. Analyzing photographs taken through various color filters by the Voyager 2 spacecraft, they found that the ratio of green light to violet light varies widely over Umbriel's surface. — Science News, 16 Nov. 1991
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!
First Known Use of umbriel
Seen and Heard
What made you want to look up Umbriel? Please tell us where you read or heard it (including the quote, if possible).