say it: ahrk-TUUR-uhs
arcturus is a noun meaning "the 4th brightest star and the brightest star in the constellation Bootes; 36 light-years from Earth". It carries one recorded sense.
the 4th brightest star and the brightest star in the constellation Bootes; 36 light-years from Earth
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for arcturus come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.