There are several theories as to how the Vikings got their name. One is that the word ‘Viking’ derives from the old Norse ‘vik’, which means creek or bay, referring to the harbours where they moored their ships. Another theory is that the name comes from the region known as the Viken, around the Oslofjord in Norway, though this would be somewhat misleading as many Vikings came from other parts of Norway, as well as Sweden and Denmark and even further afield. In Old Norse, to go a-viking (fara i viking) was to set out on a raid, so perhaps the most likely origin of the word means some kind of raider.
They were rarely called Vikings by their victims. In the Anglo-Saxon Chronicle they were often referred to as Danes, while elsewhere, such as in Francia (which covered modern France, the Low Countries and much of Germany) they were called Northmen, from which the word ‘Norman’ derives. The suggestion of a specific national origin for the raiders is misleading: so-called Danish armies that invaded England, for example, often had warriors from Sweden and Norway among their number. There is even archaeological evidence that men might have come from as far away as Finland, Poland and Belarus on occasion.