The Old Scandinavian (Old Norse) language

 
Group Germanic (with English, German, Gothic etc.), North Germanic (with Danish, Faroese etc.)
Geography Spoken by Germanic tribes on the south of the Scandinavian peninsula and in Denmark.
History Numerous inscriptions written in Runes were found in southern Sweden and in Denmark - most of them date back to the 3rd - the 9th centuries AD, long before Scandinavians were converted into Christianity. Another source for studies is the vocabulary of Finnish words borrowed from Old Norse. After the 9th century Old Norse broke into several separate tongues, including Swedish, Norwegian, Danish, and Icelandic.
Phonetics Through the period of the existence the language's phonetic system changed greatly. The early stage still preserved the stem vowel, as we can see from Norse loanwords in Finnish (Finnish jukko 'yoke', but Old Icelandic ok). The early Old Norse kept the initial j-, while later it was dropped (Finnish juusto 'cheese', but Old Icelandic ostr). The Germanic *-z in the endings of nouns was preserved as the sound R under the law of rhotacism. Different vowel mutations in the root make the language quite archaic.
Nominal Morphology The language was highly flective, presenting all five Germanic noun cases, and the variety of declension types. Adjectives could be both strong and weak. The article did not exist, though later it developed in the post-nominal position in Scandinavian languages. Personal pronouns had three numbers, including dual.
Verbal Morphology The verb of Old Norse does not differ a lot from that of the Icelandic language. The system of analytical tenses begins to form, and all the verbs were divided into strong, weak and preterite-present (modal). 
Lexicon The vocabulary of Old Norse is known scarcely from runic incriptions, but its descendant the Icelandic language with its sagas demonstrates how rich the language used to be in Scandinavia. It was also quite pure, with practically no borrowed words. A great lot of Germanic words cannot be found in any other Indo-European languages, and so they are sometimes considered as the substratum lexicon, left from aboriginal tribes of Northern Europe.
Writing Runic alphabets
Close Contacts Contacted with Finnish and Saami languages in the north, and with other Germanic languages in the south. There are also some elements borrowed from Slavic (like *turg 'market').
Sample ek wiwaR after woduri
dewitadahalaiban worahto r
R woduride staina
ūrijoR dohtriR dalidun
arbijarjosteR arbijano.

I, Wiwaz, wrought (the runes) according to Woduridaz, the bread keeper (lord). For me, Woduridaz, three daughters, the most legitimate-to-inherit of heirs, prepared the stone. (Tune Stone, c. 400 AD.)

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