Eridanus

noun

Erid·​a·​nus i-ˈri-də-nəs 

astronomy

: a southern constellation that is visible stretching between the constellations of Orion and Phoenix and that is represented by the figure of a river

How can you tell whether a galaxy is turned on or not? A team of astronomers set out to answer that question by making a series of detailed radio, infrared, optical, and spectroscopic observations of an unusual spiral galaxy in Eridanus.

—Astronomy, August 1990

Word History

First Known Use

1599, in the meaning defined above

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!