Old Norse: wargr 'wolf', literaly 'outlaw'
Evil wolves, servants of Sauron and allies of the Orcs, used by the latter as steeds. They appear to frequent in Rhovanion. The wolves that attacked the Fellowship on their way to Moria were not Wargs.
Tom Shippey suggests that Tolkien's wargs are a mixture of these two prominent meanings, because wargs are more intelligent and vicious than ordinary wolves.
|Annotations and Comments|
vargr, etymologically, shows the relation to Old Indian vrka[Kluge: Etymologisches Wörterbuch]. Proto Indo-European? wī-ro- for 'man' - especially for 'vigorous' man like warriors or slaves (since they were often captured warriors) - had several other meanings, 'werewolf' being one of them .
Grimm mentions an Old High German warg  and connects it with a - late - conception of a were-wulf and soul-snatching devil. The ability to change into a wolf and back is called lycantropy (from Greek lykos, 'wolf' + anthropos, 'man'), just like Tolkien's 'bear-man' Beorn, the skin-changer, changes into a bear and back.
Frazer and Graves both draw a connection of wolves to a corn-spirit , in Germanic and Norse mythology Skaği and Hel/Holla are connected with wolves or wolf-dogs.
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