Varangian (n.)

one of the Northmen who ravaged the Baltic coast in 9c. and by tradition overran part of western Russia and founded a dynasty there," 1788, from Medieval Latin Varangus, from Byzantine Greek Barangos, a name ultimately (via Slavic) from Old Norse væringi "a Scandinavian," properly "a confederate," from var- "pledge, faith," related to Old English wær "agreement, treaty, promise," Old High German wara "faithfulness" (from PIE root *were-o- "true, trustworthy"). Attested in Old Russian as variagi; surviving in Russian varyag "a peddler," Ukrainian varjah "a big strong man."