Arcturus

American  

[ahrk-toor-uhs, -tyoor-] / ɑrkˈtʊər əs, -ˈtjʊər- /

noun

Astronomy.

1. a first-magnitude star in the constellation Boötes.

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Arcturus British  

/ ɑːkˈtjʊərəs /

noun

1. the brightest star in the constellation Boötes: a red giant. Visual magnitude: –0.4; spectral type: K2III; distance: 37 light years

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Arcturus Scientific  

/ ärk-tr′əs /

1. A giant star in the constellation Boötes. It is the brightest star in the Northern Hemisphere and the fourth brightest star in the sky, with an apparent magnitude of 0.00. Scientific name: Alpha Boötes.

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Other Word Forms

• Arcturian
  adjective

Etymology

Origin of Arcturus

1352–75; < Latin < Greek Arktoûros, equivalent to árkt ( os ) bear + -oûros keeper; replacing Middle English arture < Middle French

Example Sentences

See Examples For:

Arcturus

Nor do they usually follow a “prophet” who claims to have come from the star Arcturus.

From The Wall Street Journal ● May 28, 2026

To find the area of sky where it should appear, she advises to first locate the plough and follow its handle to Arcturus.

From BBC ● Dec. 30, 2024

Vega, then, is a bluish-white A-type star, Arcturus is an orange K, and Antares is a red M-type.

From Scientific American ● Aug. 25, 2023

XBB.1.16, nicknamed Arcturus, has fallen to second place, and is estimated to comprise 15.6% of specimens.

From Los Angeles Times ● Aug. 10, 2023

Boötes is not specially interesting for our purposes, except for the splendor of Arcturus.

From Astronomy with an Opera-glass A Popular Introduction to the Study of the Starry Heavens with the Simplest of Optical Instruments by Garrett Putman Serviss