√PED “slope, slant down”
This root first appeared in The Etymologies of the 1930s as unglossed ᴹ√PEN with extended form ᴹ√PÉNED from which the main words in its entry were derived: ᴹQ. penda “sloping down, inclined”, ᴹQ. pende “slope, downslope, declivity” and N. penn “declivity” (Ety/PEN). The last of these has a precursor in Early Noldorin Word-lists from the 1920s: ᴱN. benn “inclined, sloping” or “slanting, sloping, up or down hill”, along with a noun form ᴱN. binn “slope”, apparently derived from the adjective plural (PE13/138, 160). This earlier form is reflected on several rejected roots in The Etymologies, with ᴹ√BEND >> ᴹ√DEN >> ᴹ√PEN (EtyAC/DAT, DEN).
In later writings, Tolkien generally gave the base root as √PED, a change Tolkien seems to have introduced to avoid conflict with a new root √PEN “lack, not have” (PE17/171, 173). The root was variously glossed “incline, slope” (PE17/171), “fall in steep slant, incline, slope” (PE17/173) or “slope, slant down” (WJ/375); all these notes date to 1959-60. Tolkien went to say that “strong forms [were] lost in Quenya owing to similarity to √PER half” (PE17/173). Indeed, in this period like in the 1930s, all the actual derivatives (in both Quenya and Sindarin) seem to be based on √PEND-, so it may be easier to assume that this was the true form of the root.
√PEL “fence, border, edge; bound, limit; go round, encircle; [ᴹ√] revolve on fixed point”
This root was connected to fences, encirclement and rotation for much of Tolkien’s life. It first appeared as two distinct roots in the Qenya Lexicon of the 1910s. The first was ᴱ√PELE¹ “fence in” with derivatives like ᴱQ. pelin “fenced in, pent”, ᴱQ. pelto “hedge, hedged field”, and ᴱQ. pelle “town” (QL/73). It had some clear derivatives in the contemporaneous Gnomish Lexicon such as G. pel “village”, G. pelu- “fence, enclose”, and G. pless “hedge, fence” (GL/64). The second root in the Qenya Lexicon of the 1910s was unglossed ᴱ√PELE² with derivatives like ᴱQ. pelko “leg”, ᴱQ. pelte- “run”, and ᴱQ. peltas “pivot” (QL/73), but the “leg” word in the Gnomish Lexicon was unrelated: G. bactha “a leg” (GL/21).
Indeed, in Quenya the “leg” word was also shifted to a new root by The Etymologies of the 1930s: ᴹ√TELEK > ᴹQ. telko “leg” (Ety/TÉLEK). As for the root ᴹ√PEL, it was given the gloss “revolve on fixed point” in The Etymologies and seems to be a blending of 1910s ᴱ√PELE¹ and ᴱ√PELE², with derivatives like ᴹQ. pel- “go round, revolve, return” and ᴹQ. peltas/N. pelthaes “pivot” (Ety/PEL) but also ᴹQ. peler/N. pêl “fenced field” and ᴹQ. opele/N. gobel “walled house or village, town” by way of extended root ᴹ√PEL(ES) (Ety/PEL(ES)).
The root √PEL appeared a number of times in Tolkien’s later writings with glosses like “edge, bound, fence, limit” (PE17/65), “fence, border” (PE17/90) and “go round, encircle” (SA/pel). Tolkien declared that:
The basic sense should not be “revolve”; but “edge, bound, fence, limit”. Thus [S.] pelennor = fenced land; ephel, Sindarin < eppel < etpel = “outer wall or fence”; [Q.] peltakse- (peltas) should mean a fence of fixed stakes etc., or a “pale” and fencing stakes; and pelma a border, fringe, edge, limiting device (PE17/65).
Tolkien reassigned the sense “revolve” to the root √KWER. The most notable derivative of the new sense “boundary” for √PEL was Q. pella “beyond”, more literally “beyond the boundary” (PE17/65, 80); this word was likely Tolkien’s motivation for removing the sense “revolve” from √PEL.
√PEN “lack, be without, have not”
A root appearing in various notes from around 1959-60 with glosses like “lack” (PE17/144), “lack, have not” (PE17/173), and “lack, be without” (WJ/375). The root clearly entered the Eldarin languages to explain the name S. Iarwain Ben-adar “Oldest and Fatherless” of Tom Bombadil (LotR/265), but Tolkien expanded its use from there.
√PEÑ “*lip, mouth”
The word Q. pé was the main Quenya word for “lip(s)” for all of Tolkien’s life, but its derivation evolved over time. The root first appeared as unglossed ᴱ√PĒ in the Qenya Lexicon of the 1910s with the derivative ᴱQ. pé “the two lips, the (closed) mouth” (QL/72). The contemporaneous Gnomish Lexicon compared this Qenya word to G. beg “chin” or “beard” (GL/22), hinting that the actual root might have been *ᴱ√BĒ. In the Declension of Nouns from the early 1930s, the primitive form was given as PĒ “lips, mouth” (PE21/1, 38). In The Etymologies of the 1930s the root became ᴹ√PEG “(?outer) mouth” with derivative ᴹQ. pé “mouth” (Ety/PEG; EtyAC/PEG).
In Common Eldarin: Noun Structure from the early 1950s the root is given as unglossed √PEÑ (PE21/71), and in notes associated with the Quendi and Eldar essay of 1959-60 the primitive form is given as peñe (VT39/11). In both cases it was an example of a primitive form that resulted in ancient monosyllabic nouns from ancient consonant loss: √PEÑ > ✶pē. In notes from the late 1960s Tolkien again gave ✶pē in a list of primitive monosyllabic nouns, but said “of these all except pe, su had probably lost a consonant in Common Eldarin”, implying the original form was actually √PĒ. But in green-note revisions made in 1970 to Outline of Phonology Tolkien had:
ñ disappeared prehistorically, so that words such as peñ were for Quenya long monosyllabic nouns with only an initial consonant: pē (PE19/102 and note #168).
Thus it seems lost the ñ in √PEÑ was restored, though it could also be a remnant of the earlier version of this sentence from the 1950s that gave both peñ and maʒ as examples of consonant-loss.
Neo-Eldarin: For purposes of Neo-Eldarin, I think it best to assume the root is √PEÑ.
√PER “half; [ᴹ√] divide in middle, halve”
This root first appeared in The Etymologies of the 1930s as ᴹ√PER “divide in middle, halve” with derivatives like ᴹQ. perya- “halve” and N. perin “half” (Ety/PER). It reappeared in notes from around 1959-60 as √PER “half” (PE17/171, 173). In Tolkien’s earliest writings, the sense “half” was assigned to the root ᴱ√LEHE or ᴱ√LEFE² instead (QL/52; GL/53).
ᴹ√PERES “affect, disturb, alter”
A root in The Etymologies of the 1930s glossed “affect, disturb, alter” with derivatives like N. presta- “to affect, trouble, disturb” and N. pesso “it affects, concerns” (Ety/PERES; EtyAC/PERES). It had a short form ᴹ√PER (EtyAC/PERES), but in a separate entry in The Etymologies ᴹ√PER was glossed “divide in middle, halve” (Ety/PER) which doesn’t seem to be related.