√RED “scatter, sow”
This root first appeared as ᴹ√RED “scatter, sow” in The Etymologies of the 1930s along with augmented variant ᴹ√ERÉD and derivatives like ᴹQ. erde/N. eredh “seed, germ” and ᴹQ. resta/N. rîdh “sown field, acre” (Ety/ERÉD, RED). √RED appeared again in the Outline of Phonology (OP2) from the early 1950s with the same gloss “scatter, sow” and derivatives Q. resta/S. rîdh “sown field” (PE19/91). The Quenya word resta reappeared in the 1964 phrase Q. nai elen siluva parma-restalyanna meldonya “*may a star shine upon your book-fair, my friend” (VT49/38), which might indicate the ongoing validity of this root, but it is also quite possible that resta “*fair” has a completely different etymology.
ᴱ√REÐE “kinsman”
The form reðe was a root added under ᴱ√RESE [REÞE] “aid, support” in the Qenya Lexicon of the 1910s, with derivatives of ᴱ√RESE having to do with “kinship” reassigned to reðe, such as ᴱQ. renda “related, of the same kin or clan” and ᴱQ. resse “kinswoman, cousin” (QL/79). In the contemporaneous Gnomish Lexicon Tolkien had a similar set of words likewise derived from distinct reth- vs. redh-, with the latter most likely being the basis for words like G. redhin “related” and G. ress “cousin (f.), relative” (GL/65). The root was given as RESE- “kinsman” in the Poetic and Mythological Words of Eldarissa (PME/79), but the addition of reðe may be later than that document.
Neo-Eldarin: For purposes of Neo-Eldarin, I think it is worth positing a Neo-Root ᴺ√RE(N)D to preserve these early kinship and cousin words, for which we have no later alternatives. It might be considered a variant of later root √RED “scatter, sow” (Ety/RED; PE19/91) and thus applied only to more distant kin.
ᴹ√REG “edge, border, margin”
A root in The Etymologies of the 1930s glossed “edge, border, margin” with derivatives like ᴹQ. réna of similar meaning and N. rhain “border” (Ety/REG). ᴹ√REG replaced a rejected variant ᴹ√RAG (EtyAC/REG). The root is evident in only one name: N. {Duil Rain >>} Emyn Rhain “Border Hills” in Lord of the Rings drafts from the 1940s (TI/268, 313), called S. Emyn Muil “Drear Hills” in the published version of The Lord of the Rings (LotR/373; RC/334).
√REK “recover, save (from ruin, peril, loss), get out or away”
A root glossed “recover, get out/away, save from ruin/peril/loss” in notes on the words from The Lord of the Rings, serving as an explanation for S. edraith “rescue, saving” (PE17/38).
√REM “entangle, snare, trap”
A root appearing with forms √REB and √REM in notes from 1969 (VT42/12), first appearing as √REB alone (VT42/29 note #28). It was glossed “entangle, snare, trap (as hunters or fishers) with lines or nets” and had derivatives like Q. remi “snare”, Q. rembë/S. rem(m) “net (for catching)”, and Q. rembina/S. remmen “entangled”. The last of these appeared as an element in a couple words in The Lord of the Rings: S. galadhremmin “tree-meshed” or “tree-woven” (LotR/238, 1115; PE17/136) and S. Remmirath “Netted Stars” or “Netted Jewels” (LotR/81; PE17/24). Most of this root’s derivatives are from strengthend remb-, but the forms Q. remi and Q. remma “snare” can only be derived from √REM (VT42/12).
√RETH “remain in same place”
A root appearing in a list of Sindarin words placed with Definitive Linguistic Notes (DLN) from 1959, given as √REÞ or √RES “remain in same place, hence be unmoved, patient”. It had the derivatives S. andreth “patience”, which appeared elsewhere as the name of a Bëorian woman (MR/305), and S. Arodreth “Noble Endurance”, a name appearing nowhere else. The variant √RES may have been intended to be the Quenya form.
ᴱ√REÞE “aid, support”
A root given as ᴱ√RESE “aid, support” (gloss marked with a “?”) in the Qenya Lexicon of the 1910s, but Tolkien later decided that it was confused with another root ᴱ√reðe which seemed to do with kinship (QL/79). After this change, forms derived from ᴱ√RESE “aid” probably still included ᴱQ. resta in the sense “support”, as well as ᴱQ. resta- “aid, come to aid of, rescue, save”. In the contemporaneous Gnomish Lexicon Tolkien has a similar set of words likewise derived from distinct reth- vs. redh- (GL/65), indicating the true form of ᴱ√RESE was probably ᴱ√REÞE, since þ became s in Qenya. As Gnomish derivatives of reth- Tolkien initially gave G. rest¹, G. resta-, G. reth- (GL/65), but these were deleted leaving only G. grest “succour, salvation”, G. gresta- “aid, help, succour, support”, and G. gretha- “save, rescue, preserve” (GL/42).
It is possible the root ᴱ√REÞE reemerged as √REK “recover, get out/away, save from ruin/peril/loss” given in Tolkien’s later writings as the basis for S. edraith “rescue, saving” (PE17/38).
Neo-Eldarin: For purposes of Neo-Eldarin I think it is worth positing a (Sindarin only) Neo-Root ᴺ√(G)RETH to salvage some of these Gnomish words.