A word for the (closed) mouth (PE21/70; PE17/126) which Tolkien sometimes used as “lip” (VT39/9; VT47/12); see below. Its dual form peu referred to “the two lips, the mouth-opening” (VT39/9), as opposed to a single lip which seems to be Q. pempë (PE17/126).
Conceptual Development: This word dates all the way back to the Qenya Lexicon of the 1910s, where Tolkien gave ᴱQ. pē “the two lips, the (closed) mouth” from primitive ᴱ√PĒ (QL/72). In the contemporaneous Gnomish Lexicon, ᴱQ. pê was simply glossed “mouth” and was connected to G. beg “chin” (GL/22), indicating that the early root might actually have been ✱ᴱ√BĒ since primitive initial voiced stops were unvoiced in Early Qenya.
ᴱQ. pē “mouth” reappeared in a list of body parts from the 1920s (PE14/117), and ᴹQ. pé “mouth” appeared again in the Declension of Nouns from the early 1930s as an example of vocalic monosyllabic noun from primitive ✶pē (PE21/38); at the beginning of this document the primitive form was glossed “mouth, lips” (PE21/1). In The Etymologies of the 1930s it was ᴹQ. pé “mouth” derived from the root ᴹ√PEG (Ety/PEG); this entry had a difficult-to-read word inserted before its gloss, possibly “outer”, so perhaps the meaning was revised to “outer mouth” (EtyAC/PEG).
In the 1950s and 60s, the word pé was generally derived from √PEÑ (PE19/102; PE21/70; VT39/11). In notes associated with the Quendi and Eldar essay of 1959-60, Q. pē was glossed “lip” and its dual peu referred to “the two lips, the mouth-opening” (VT39/9). In 1964 notes on parts of the mouth Tolkien glossed pē as “the closed mouth” (PE17/126), but in notes from 1968 it was again glossed “lip” (VT47/12). In notes on monosyllabic nouns from this period Tolkien said ✶pē “lip” was a primitive monosyllabic vocalic noun, but that it was reduplicated to ✶pē̆pe (VT47/35). In green-ink revision to Outline of Phonology from around 1970, Tolkien again affirmed the original primitive form was pe(ñ), though the ñ was lost very early (PE19/102 note #102).
Neo-Quenya: For purposes of Neo-Quenya, I would use pé as a word meaning “mouth”, more specifically for “closed mouth” as opposed to the general word for mouth: Q. anto. For a single “lip” I would use pempë, but I would use peu as a dual form indicating both lips, whether open or closed. All these words are in general use, but pé is also used as a technical term in linguistic discussions for the close mouth in formation of consonants such as voiced and voiceless stops.
pé noun "lip", dual peu "the two lips, the mouth-opening" (VT39:9; VT47:12, 35). In an earlier source, the Etymologies, pé was glossed "mouth" (PEG), whereas in PE17:126 it is more specifically "the closed mouth".