Viking is a term with many meanings, and depending on whom you are talking to, you may get a different response.
In the SCA (as in much of modern western media) the word Viking is currently used to refer to any of the Norse people from between (about) the 500s to (about) the 1300s. Whether this is an accurate usage is a matter of energetic disagreement.
Some of the various positions in this disagreement are that Viking:
- refers to any Norseman from the period mentioned.
- refers to ?wanderers?, or Norse who traveled about.
- specifically Norse merchants that traveled about during the period in question.
- refers specifically to those western Scandanavian pirates and marauders that ravaged northern and western Europe between the 8th and 11th centuries.