Umbriel

noun

Um·​bri·​el ˈəm-brē-ˌel 

astronomy

: 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

Word History

First Known Use

1874, in the meaning defined above

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