The Terms Rus and Varangian
Rus’ and Varangians: Stefan Brink gives the following comment on the etymology of the term Rus’:
“The ones who travelled on the rivers in Russia could be called Rus’ or Væringar. The word Rus’ is most certainly to be connected to the name of the province Roslagen, the eastern part of the province of Uppland in Sweden , which we also find in the Finnish name for Sweden, which is Routsi. The word goes back to the words ro ‘row’ and rodd ‘a rowing session’. One idea is that the word Rus’ for a Swede was succeeded by the word væringr, væringi, in Russian varjag. The explanation put forward for this latter word is quite interesting. It is supposed that it emanates from the titles of the Scandinavian guard of the Byzantine emperor in Constantinople, as a member of his personal bodyguard. The word probably has the meaning of a person who has given an oath of fidelity (ON *vár ‘oath, promise’), obviously to the emperor. From here the word, so the hypothesis is, was later on transferred to a Swede or a Scandinavian in general.”
Brink, S., (2008), “Who were the Vikings?”, in Brink, S. & Price, N. (eds), “The Viking World”, Routledge, pp 4-5
Varangians: “(ON Væringjar, Slavik Variazi, Greek Varaggoi, Arabic Warank) A term used by Greeks, Arabs and Slavs to describe Scandinavians. Though the Rus are sometimes described as Varangians, indicating their Scandinavian origins, the term is more usually reserved for Scandinavian merchants and mercenaries newly arrived in the east from their homelands. In English and the Scandinavian languages, the term is generally used more narrowly to describe members of the Byzantine emperor’s élite bodyguard, the Varangian Guard. The word ‘Varangian’ is probably derived from Old Norse vár, meaning ‘pledge’, possibly because bands of Scandinavian merchants and warriors customarily formed sworn fellowships.”
Haywood, J. (2000) “Encyclopaedia of the Viking Age”, Thames and Hudson, London, pp 197-8.