Contrary to the way the word has been used in this thread,
and contrary to the popular concept, the word "Viking" does
not refer to a particular people, as does "Norse" or "Dane".

"Viking" refers to an activity (maybe it could be called
a lifestyle).

A farmer, let's say, in the Scandinavian area decides that
he'd like an adventure, with the possibility of gaining riches
and slaves for sale, and maybe finding, conquering, and occupying
better agricultural land. What does he do? He "goes Viking"
--that is, he goes raiding places like Ireland or England or
what we today would consider northern France. While engaged in
that sort of activity, he's a Viking.

If he's satisfied with his loot from that year's raids, or
if he's been defeated, (or maybe he's homesick) possibly
he goes back home to what today is Denmark or Sweden, to
his farm and family, there maybe to plan and organize next
year's raids. But he's still a Dane or a Swede, whether
he's "out Viking" or at home, farming or whatever.

Just being a far-ranging seaman, or an explorer, doesn't
make him a Viking. It's the warlike raiding activity
that does that, while he's at it.

Dave Oesterreich