erne (n.)

masc. proper name, from Old High German Arenwald, literally "having the strength of an eagle," from arn "eagle," from Proto-Germanic *aron- "eagle" (from PIE root *or- "large bird;" see erne) + wald "power" (from PIE root *wal- "to be strong").

masc. proper name, from Medieval Latin Arthurus/Arturus, usually said to be from Welsh arth "bear," cognate with Greek arktos, Latin ursus (see arctic). The name was perhaps *Arto-uiros, "bear-man" though another theory links it with the rare Roman name Artorius, and another with the star Arcturus. (See Thomas Green's Concepts of Arthur, Chapter 5 for his research into the matter.) Until the middle ages the name was rarely seen outside of the mythic Welsh legends of King Arthur.

Reference to King Arthur probably also is the source of Arthur's Seat, hill in Scotland so-called by 1650s. Arthur, in pre-Galfridian literature, commonly was conceived as a giant, which might explain a hill as a seat, but Dictionaries of the Scots Language refers seat in Scottish place names to Gaelic suidhe "a high, gen[erally] saddle-shaped and conspicuous hill ...."