I have seen it written in many places that the name Yordas comes from the Old Norse jord ass (or jord aas) meaning 'Earth stream'. I am no Old Norse scholar but, whilst j?r? certainly seems to be the word for earth, I cannot find any source for the word ass or aas meaning stream.

The Old Norse word ?ss, as far as I can tell, meant god - as used in ?sgar?r, the enclosure of the gods. Can anyone point me to a better Old Norse dictionary?

It's arse, dammit!

Oh sorry, just read beyond the title....

?s means hill. Who knows the truth of what Odd was up to.

I once had an office next to ones inhabited by Odd and Even. I jest not.

I have a vague memory of a conversation (from a long time ago) with someone who had been caving in Norway who referred with a smile to an "Aas Hohle". Apparently it was translated as "stream cave". This may not be entirely reliable.

In modern Icelandic (which I understand is very close to old Norsk), j?r? means ground, many lava tube cave entrances are described as jar?fall, literally "ground falls" where the cave roof has collapsed.  Stream translates as ?, the spectacularly named Jokulls? ? Fj?llum translating very roughly as the Ice (or Glacier) River of the Mountains.  The river is also pretty spectacular, especially at the huge waterfall of Dettifoss.

So I reckon their may be some truth in the derivation of Jordas coming from "Ground/Earth Stream".  Icelandic for cave is Hellir (pronounced roughly as hed-ler) so the original norsk name may have been something like J?r??hellir and prounounced something like Yorthawhedler.

My copy of Longman's "Norse Myths and Legends" book (by J. H. Walsh, first published 1957) refers to the "Asa Gods" - the first gods to be created.

However, this resource does suggest that "a" can mean a river: https://glosbe.com/en/non/river

As does this: https://www.wordhippo.com/what-is/the-meaning-of/swedish-word-a.html

Apparently "As" is also a Swedish male name.

JasonC was close:
https://en.m.wiktionary.org/wiki/rassh%C3%B8l