Greetings from Stuntie
Two things:
English -s
Modern words in Old Norse
English -s/-es comes from Anglo Saxon -as the Nom. Pl. ending of most nouns.
This is derived from the same root as the -r (Mdn. Ice. -ur) of Old Norse.
Genitive -s just happens to be the same, but comes from a different root.
When languages begin to coalesce case, as happened in English and all three
of the Mainland Scandinavian languages, then the most common endings become
the dominant form. Only the distinctions of person (singular and plural) and
possession are marked now in these languages. In English both these endings
are -s, but that's just a fluke of nature.
-es (-ies) is just a phonetic modification when the consonant cluster
with -s is hard to pronounce.
All this started way before the mass influx of foreign words. Its a natural
part of the way some languages develop.
Remember Old Norse and Anglo Saxon derive from Proto-Germanic (spoken in
Germany around the Roman period) but are very different to look at. Its just
language evolution.
English and Swedish have had very little contact, but evolved along very
similar lines.
Loan words are a problem for the modern world as the pace of technology and
the globalisation of languages has resulted in a much larger number of new
words than normal.
Previous explosions of new concepts were dealt with, and so shall this one.
e.g. Prestr (priest) and kirkja (church) were originally loanwords in Old
Norse.
Why does everyone keep asking how to use foreign words in Old Norse?
Why does everyone keep treating Old Norse like some dead language, similar
to Anglo Saxon.
A) Its not dead.
Its just called Icelandic nowadays.
Just ask any Icelander, It's not changed that much since the time of the
Vikings.
Its like Shakespeare's English, that's perfectly readable even with its
thee's and doth's
Anglo Saxon is dead - no native speakers exist, and it is incomprehensible
to Modern English speakers.
B) The Icelanders are a modern up-to-date people so why not ask them.
Any good Icelandic dictionary can give you all those nice new 'foreign'
words. Just modify them to fit Old Norse.
And what you will find is new words based on other Icelandic words which fit
perfectly into the grammar system.
C) The standard rules for compounds in Old Norse, as in modern Icelandic, is
that a word is declined according to the last element. e.g. geisladiskr
(Mdn. Eng - Compact Disk) (which I have derived from Mdn. Ice. geisladiskur)
would decline the same as diskr.
The only question is whether using words not found in the Old Norse lexicon
is allowable.
A strict interpretation is that it is not.
Only words found in sources can be used, and only in those contexts found
there.
If you that's being pedantic try asking Old Norse lecturers to clarify a
grammatical topic by posing a hypothetical sentence to them. Many will not
even comment on a sentence unless it can be found in the sources.
But other people want different things from Old Norse.
To be able to converse in Old Norse would necessitate use of words not
attested to, and would involve the person saying sentences that have not
been recorded in the sources.
Also to be able to formulate practice sentences for a course would require a
much less strict interpretation.
To me the distinction is between source material, and any other use.
If its not from a documented source it is not original.
I have no objections to anyone writing, speaking or whatever in Old Norse,
as long as they do not claim it to be an original source.