[ ahrk-too r-uh s, -tyoo r- ]
/ ɑrkˈtʊər əs, -ˈtyʊər- /

noun Astronomy.

a first-magnitude star in the constellation Boötes.

Origin of Arcturus

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

Related forms

Arc·tu·ri·an, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for arcturian

  • It was forty feet long, eight wide, and eight high; the tank containing the Arcturian back rays was in front, the car behind.

    A Voyage to Arcturus|David Lindsay
  • They are of a spectral type approximately solar; no Orion, Sirian or Arcturian stars having been found among them.

  • It was a gentle dig at his Arcturian homeland, which was smaller than most planets.

    Youth|Isaac Asimov
  • For twenty-four hours on that Arcturian planet, I would give my life.

    A Voyage to Arcturus|David Lindsay

British Dictionary definitions for arcturian


/ (ɑːkˈtjʊərəs) /


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

Derived Forms

Arcturian, adjective

Word Origin for Arcturus

C14: from Latin, from Greek Arktouros, from arktos bear + ouros guard, keeper
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for arcturian


[ ärk-turəs ]

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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.