The root ᴹ√GOR “violence, impetus, haste” first appeared in The Etymologies of the 1930s with derivatives like ᴹQ. orme “haste, violence, wrath” and N. gorn “impetuous” (Ety/GOR), along with a variant ᴹ√ƷOR whose only derivative was ᴹQ. orro or horro “ugh, alas!, ow!” (EtyAC/ƷOR). The root √GOR reappeared in 1968 notes on Gender and Sex with the gloss “deep, profound”, and there it served as the basis for órë (see below) along with other derivatives like Q. orda “profound”, S. gœria- “to ponder”, and S. gordh “deep thought” (NM/176). The root appeared again in another essay from 1968 on the topic of órë (VT41/11-15; NM/219-224), where Tolkien explained its meaning as follows:
> Nearest to the original sense is “warn”, but (a) it did not refer only to dangers, evils, or difficulties ahead; and (b) though it could be used of the influence of one person upon another by visible or audible means (words or signs) — in which case “counsel” was nearer to its sense — this was not its chief use. This can best be explained by consideration of its principal derivative. This was in Common Eldarin ✱gōrē: Quenya óre, Telerin ōre, Sindarin gûr (NM/219).
Tolkien went on to explain Q. órë as the source of deep emotions, that “advises, but is never represented as commanding”, roughly analogous to one’s conscience; see the entry on Q. órë for further details. Note that when this essay on órë was first published in Vinyar Tengwar 41 in the year 2000, Carl Hostetter gave the root and the primitive form as √ƷOR and ✱ʒōrē (VT41/11), but in his book The Nature of Middle-earth (NM) from 2021, he corrected them to √GOR and ✱gōrē (NM/219).
In rough notes after the main essay, Tolkien altered the root to √HOR with glosses “urge, impel, move” specifically limited to “mental impulses” (VT41/13; NM/221). This revised form might be a later iteration of ᴹ√KHOR “set going, put in motion, urge on” from The Etymologies (Ety/KHOR) as suggested by Carl Hostetter (VT41/17 note #9). Tolkien gave the Quenya derivative of this revised form as (h)óre but did not specify its Sindarin derivative (VT41/13; NM/222). In another rough note in the same bundle he gave [primitive?] hor- “warn” as the basis for T. hŏra or ora and Q. óre (VT41/15).
Neo-Eldarin: The root √HOR is problematic and difficult to reconcile with either Q. óre and S. gûr, since typically primitive h- survived in Quenya but vanished in Sindarin. I think it is preferable to assume the root remaining √GOR. As for its meaning, I would assume the basic sense was “warn, council” as well as “mental impulse”, with ✶gorē serving as the source of deep-seated thoughts and emotions. This interpretation would allow the continued use of the majority of the root’s attested derivatives from both the 1930s and 1960s, including various 1930s words having to do with “haste” and “impetousness”.
This root was connected to “heat” for most of Tolkien’s life. It first appeared as unglossed ᴱ√URU in the Qenya Lexicon of the 1910s, with derivatives like ᴱQ. úrin “(blazing) hot”, ᴱQ. uru “fire”, G. urin “hot, very hot”, and G. urna- “blaze, burn” (QL/98; GL/75). In this early period it was blended with the root ᴱ√UŘU with variant ᴱ√USU which had derivatives like ᴱQ. urna “oven” and ᴱQ. usta- “burn” (QL/98). This second root had derivatives in the contemporaneous Gnomish Lexicon such as G. gund “boil, pus” and gusta- “burn, destroy” from primitive ✱gudh (GL/42), indicating the actual root form was ✱ᴱ√ƷUÐU.
✱ᴱ√ƷUÐU seems to have been abandoned in Tolkien’s later writings, but ᴹ√UR “be hot” appeared in The Etymologies of the 1930s with derivatives like ᴹQ. úr/N. ûr “fire” and ᴹQ. urya- “blaze” (Ety/UR). This entry was deleted and replaced by ᴹ√UR “wide, large, great”. This was likely a transient change, however, as ᴹQ. Úrin as a name of the Sun remained in contemporaneous Silmarillion drafts (LR/240). Indeed primitive √UR appeared several times in later writings as the basis for words for “sunlight”, “fire” and “heat” (PE17/120, 148; PE21/71; PE22/160).