Arc·​tu·​rus ärk-ˈtu̇r-əs How to pronounce Arcturus (audio)
: a giant fixed star of the first magnitude in Boötes

Examples of Arcturus in a Sentence

Recent Examples on the Web As a red giant, Arcturus is at the end of its life and will eventually transform into a planetary nebula. Elizabeth Gamillo, Discover Magazine, 5 Mar. 2024 Vega, then, is a bluish-white A-type star, Arcturus is an orange K, and Antares is a red M-type. Phil Plait, Scientific American, 25 Aug. 2023 The reddish-orange streak to the right of center and extending almost the whole picture vertically is from Arcturus. Discover Magazine, 18 July 2023 Someone pointed out Arcturus, the third-brightest star in the galaxy, then Saturn. Samantha Falewée, Travel + Leisure, 16 July 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'Arcturus.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin, from Greek Arktouros, literally, bear watcher

First Known Use

14th century, in the meaning defined above

Time Traveler
The first known use of Arcturus was in the 14th century

Dictionary Entries Near Arcturus

Cite this Entry

“Arcturus.” Dictionary, Merriam-Webster, Accessed 18 Apr. 2024.

Kids Definition


Arc·​tu·​rus ärk-ˈt(y)u̇r-əs How to pronounce Arcturus (audio)
: a very large bright star in Boötes that does not appear to move

More from Merriam-Webster on Arcturus

Last Updated: - Updated example sentences
Love words? Need even more definitions?

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