1. the 4th brightest star and the brightest star in the constellation Bootes; 36 light-years from Earth;
The Collaborative International Dictionary of English v.0.48:
Arcturus \Arc*tu"rus\, n. [L. Arcturus, Gr. ? bearward, equiv.
to ?; ? bear + ? ward, guard. See Arctic.] (Anat.)
A fixed star of the first magnitude in the constellation
Note: Arcturus has sometimes been incorrectly used as the
name of the constellation, or even of Ursa Major.
Canst thou guide Arcturus with his sons [Rev.
Ver.: "the Bear with her train"]. --Job xxxviii.
WordNet (r) 3.0 (2006):
n 1: the 4th brightest star and the brightest star in the
constellation Bootes; 36 light-years from Earth
Easton's 1897 Bible Dictionary:
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.