[Aiwendil]

Originally Posted by Inziladun

In HOME V The Lost Road and Other Writings an alternate Elvish name of "Regornion" is given. I don't have that particular volume, so I'm unsure of the translation. It was called by Tolkien "Nan-eregdos" in a draft of The Ring Goes South. I'm not aware of any Dwarven name.

The HoMe V quote is from the Etymologies, stem EREK- :

ERÉK- thorn. Q erka prickle, spine; erka- to prick; erkasse holly. N ercho to prick; erch a prickle; ereg (and eregdos [TUS]) holly-tree, pl. eríg. Cf. Taur-nan-Erig or Eregion = Dor. Forest of Region: Dor. regorn holly-tree (pl. regin, g.pl. region) [see OR-NÍ]. [Further addition:] Regornion = Hollin.

Note that here 'Eregion' is said to be Doriathrin; this text dates from before the change of Noldorin->Sindarin. The 'Eregion' mentioned here is not the Second Age kingdom in Eriador, but the forest that made up the greater part of Doriath; it seems to be identical in etymology and signification with 'Region', the more familiar name for that forest.

We don't know when the further addition 'Regornion' was made. It's obviously an alternate form, with the same etymology, of 'Eregion' and 'Region', but it's not clear whether it's intended to refer to the Doriathrin forest or the Noldorin kingdom, and it's not clear whether it was a (transitory) replacement for '(e)region', or another acceptable name alongside it. But that's probably not worth losing much sleep over; it clearly has the same etymology and meaning as 'Eregion'.

'Nan-eregdos' clearly also comes from the same root meaning 'holly'. I'm not sure what to make of the '-dos' element, but clearly the name means something like 'Vale of Holly'.

Unfortunately, none of this brings us any closer to a name for the kingdom in languages other than Sindarin and English (i.e. translated Westron).

Edit: The meaning of 'Eregdos' was right in front of me in the entry from the Etymologies, where it refers to root TUS- :

TUS- *tussā: Q tussa bush, N toss low-growing tree (as maple, hawthorn, blackthorn, holly, etc.): e.g. eregdos = holly-tree. See ERÉK, ÓR-NI.

So 'Nan-eregdos' is 'Vale of Holly Trees'.