[ahrk-toor-uhs, -tyoor-]
noun Astronomy.
a first-magnitude star in the constellation Boötes.

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

Arcturian, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
Arcturus (ɑːkˈtjʊərəs)
the brightest star in the constellation Boötes: a red giant. Visual magnitude: --0.4; spectral type: K2III; distance: 37 light years
[C14: from Latin, from Greek Arktouros, from arktos bear + ouros guard, keeper]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin & History

late 14c., bright star in the constellation Bootes (also used of the whole constellation), anciently associated with the Bear, and its name is Gk. for "guardian of the bear." See Arctic; second element is from ouros "watcher, guardian, ward." Arcturus in the Bible is a mistranslation
by Jerome of Heb. Ayish, which actually refers to the "bowl" of the Big Dipper. In Israel and Arabia, the seven stars of the Great Bear seem to have been a bier (the "bowl") followed by three mourners. The double nature of the great bear/wagon (see Big Dipper) has given two different names to the following constellation: Arktouros "bear-ward" (and bootes "the wagoner."
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
Arcturus   (ärk-tr'əs)  Pronunciation Key 
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 © 2002. Published by Houghton Mifflin. All rights reserved.
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Bible Dictionary

Arcturus definition

bear-keeper, the name given by the ancients to the brightest star in the constellation Bootes. In the Authorized Version (Job 9:9; 38:32) it is the rendering of the Hebrew word _'ash_, which probably designates the constellation the Great Bear. This word ('ash) is supposed to be derived from an Arabic word meaning night-watcher, because the Great Bear always revolves about the pole, and to our nothern hemisphere never sets.

Easton's 1897 Bible Dictionary
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Encyclopedia Britannica


one of the five brightest stars in the night sky, and the brightest star in the northern constellation Bootes, with an apparent visual magnitude of 0.05. It is an orange-coloured giant star about 37 light-years from the Earth. It lies in an almost direct line with the tail of Ursa Major (the Great Bear); hence its name, derived from the Greek words for "bear guard."

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences for Arcturus
It contains the third brightest star in the night sky, arcturus.
Image for Arcturus
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