Take for example German, assumed to be a single language. There are varieties of German which are not understood by speakers of other varieties. One thing for certain - 'language' is not a particularly linguistic notion at all. The reason why Norwegian, Swedish, Danish and German are thought of as single languages has as much to do with political, geographical, historical, sociological and cultural reasons, as with linguistic ones. Therefor the term 'language' is relatively 'unscientific'.
Linguists usually refer to 'varieties of language'.
Therefor Norwegian Swedish and Danish could be referred to as varieties of Scandinavian. Dialects and accents frequently merge into each other without any discrete break. Geographic Dialect Continua Imagine starting out on a journey by foot, from the Atlantic coast of Portugal to the southern tip of Italy. Imagine the route taken went westwards to Madrid in central Spain, and then on to Barcelona on the Mediterranean coast. Continuing northwards to Paris then south eastwards through Geneva in Switzerland and then down through central Italy.