Meaning rectified according to VT/46:10
Noldorin
rhaw
noun/adjective. wild, untamed
rhaw
adjective. wild, untamed
braig
adjective. wild, fierce
The form brerg in the Etymologies is a misreading according to VT/45:34
breig
adjective. wild, fierce
The form brerg in the Etymologies is a misreading according to VT/45:34
lhain
adjective. free, freed
lhein
adjective. free, freed
rhain
adjective. free
The Etymologies of the 1930s had N. {rhein >>} rhain “free” derived from ᴹ✶(a)ranı̯ā under the root ᴹ√RAN “wander, stray”; it also had a deleted variant erein, presumably from aranı̯ā (EtyAC/RAN). See also S. rain “erratic wandering” for a later appearance of a similarly derived word.
Neo-Sindarin: Many Neo-Sindarin writers adapt this adjective as ᴺS. rain “free” for purposes of Neo-Sindarin, as suggested in HSD (HSD), since the unvoicing of initial r to rh was a feature of Noldorin of the 1930s but not Sindarin of the 1950s and 60s. I would use it as “free” in the sense “✱unconstrained”.
According to the editorial corrections in EtyAC/RAB, the gloss “wilderness” in The Etymologies is actually associated with a different word, rhofan, so that the proper gloss of this word is likely the same as its Quenya cognate ráva: “wild, untamed”.