Proto-Norse was an Indo-European language spoken in Scandinavia that is thought to have evolved as a northern dialect of Proto-Germanic in the first centuries CE.

It is the earliest stage of a characteristically North Germanic language, and the language attested in the oldest Scandinavian Elder Futhark inscriptions, spoken from around the 2nd to the 8th centuries CE (corresponding to the late Roman Iron Age and the Germanic Iron Age).

[3] Finally, quite a number of linguists have assumed that even the first phonetic rudiments of the distinction did not appear until the Old Norse period.

Numerous early Germanic words have survived with relatively little change as borrowings in Finnic languages.

Wolfgang von Krause sees the language of the runic inscriptions of the Proto-Norse period as an immediate precursor to Old Norse, but Elmer Antonsen views them as Northwest Germanic.

Characteristic is also the Proto-Norse lowering of Proto-Germanic stressed *ē to ā, which is demonstrated by the pair Gothic mēna and Old Norse máni (English moon).

There is, however, no trace of that in the Elder Futhark runic inscriptions, so it can be safely assumed that the quality of this consonant must have changed before the devoicing, or the phoneme would not have been marked with a rune different from the sowilō rune used for s. The quality of the consonant can be conjectured, and the general opinion is that it was something between [z] and [r], the Old Norse reflex of the sound.

In Old Swedish, the phonemic distinction between r and ʀ was retained into the 11th century, as shown by the numerous runestones from Sweden from then.

However, the changes brought forth by syncope made the umlaut-vowels a distinctive non-transparent feature of the morphology and phonology, phonemicising what were previously allophones.