Piotr Gasiorowski:
>The name <Eärendil> has a transparent Quenya etymology (eär
'sea' + -ndil 'friend'), but since it also refers to the Evening Star, it
was no doubt inspired by OE e:arendel 'Venus' (by Tolkien's own admission,
these famous lines from Cynewulf's _Christ_,
Eala earendel engla beorhtast
ofer middangeard monnum sended ...
haunted his imagination since he first read them). This word is in turn
connected with ON Aurvandill (= Orvandil, a hero whose toe, thrown into the
sky by Thor, became a star; as to which star it was, opinions vary).
I'm not sure whether these assertions would still be valid, but, according
to Jacob Grimm, the word Orendel had cognates in various northern European
languages, all meaning devil [Grimm. J., "Teutonic Mythology", trans. 4th
edition 1883; 374-375]. Victor Rydberg, meanwhile, suggested that Orendel,
or Orvandel, was the northern counterpart of the god Tishtriya, who
represented Sirius. [Rydberg, V. (1889) "Teutonic Mythology": 584-586; 601;
658.]
Jean Kelly