Another possibility is that it is derived from a Brittonic patronym *Arto-rīg-ios (the root of which, *arto-rīg- "bear-king" is to be found in the Old Irish personal name Art-ri) via a Latinized form Artōrius.[10] Less likely is the commonly proposed derivation from Welsh arth "bear" + (g)wr "man" (earlier *Arto-uiros in Brittonic); there are phonological difficulties with this theory—notably that a Brittonic compound name *Arto-uiros should produce Old Welsh *Artgur and Middle/Modern Welsh *Arthwr and not Arthur (in Welsh poetry the name is always spelled Arthur and is exclusively rhymed with words ending in -ur—never words ending in -wr—which confirms that the second element cannot be [g]wr "man").[11][12] …show more content…
An alternative theory, which has only gained limited acceptance among scholars,[13][14][15][16][17][18] derives the name Arthur from the Latin Arcturus (the brightest star in the constellation Boötes, near Ursa Major or the Great Bear[19]), which is the latinisation of the Greek Αρκτοῦρος (Arktouros) and means "Guardian of the Bear",[20] ultimately from ἄρκτος (arktos), "bear"[21] + οὖρος (ouros), "watcher, guardian".[22] Classical Latin Arcturus would also have become Art(h)ur when borrowed into Welsh, and its brightness and position in the sky led people to regard it as the "guardian of the bear" and the "leader" of the other stars in