enel prep. "between" = "at the central position in a row, list, series, etc. but also applied to the case of three persons" (VT47:11). This preposition refers to the position of a thing between others of the same kind; compare imbë.
Quenya
enel
preposition. in the middle, between
enel
between
endë
noun. centre, middle, centre, middle; [ᴹQ.] core
The word ᴹQ. ende first appeared in The Etymologies of the 1930s, glossed either “middle, centre” (Ety/ÉNED) or “core, centre” (Ety/NÉD), and derived from the root ᴹ√ENED “middle” (Ety/ÉNED). In notes from late 1960s Tolkien had {ened >>} ente “centre”, which he clarified was “not used of emotions or thought only physical” (VT41/12). In this context it was derived from √HENET “middle” (VT41/16). But in other writings from the late 1960s, the word as again ende from √ENED “middle” (VT48/25), and I believe √HENET > ente was a transient idea.
Neo-Quenya: Base on its 1930s glosses and the meaning of 1960s ente, I believe ende is a noun referring to a physical centre.
entë
noun. centre
imbë
between
imbë (1) prep "between" (Nam, RGEO:67, VT47:11, PE17:92). This is "between" referring to a gap, space, barrier, or anything intervening between two other things, like or unlike one another (compare enel). The pluralized form imbi implies "among" of several things (ancalima imbi eleni "brightest among stars"); "in the sense 'among' before plurals [imbë] is usually pluralized > imbi even when a plural noun follows". As pointed out by Patrick Wynne, imbi may also be used in the sense of "between" before two singular nouns connected by "and" (as in the example imbi Menel Cemenyë "between heaven and earth"), whereas imbë is used before dual forms, as in the examples imbë siryat "between two rivers", imbë met "between us". Elided imb' in the phrase imb' illi "among all" (VT47:11, 30). A dual form imbit is also mentioned, used to express "in absolute form the sense 'between two things' when these are not named" (apparently meaning that imbit expresses *"between them" referring to two entities, with no noun following) (VT47:30, PE17:92)
neldë
cardinal. three, three; [ᴱQ.] four
endya
middle
endya > enya adj. "middle" (ÉNED)
endëa
middle
#endëa adj. "middle" in atendëa, q.v. Compare enya.
endëa
adjective. middle, middle, *average
enya
middle
enya < endya adj. "middle" (EN). Compare #endëa.
mitta
preposition/adverb. between, [ᴹQ.] inwards, into, [ᴱQ.] in; [Q.] between
A derivative of √MI “in” with various meanings throughout Tolkien’s life. It seems to mean “in” within the name Mittalmar “Inlands” from the mid-1960s. In Quenya prayers of the 1950s, it was briefly used for “among” before being revised to mika (VT43/27-28), and was glossed “between” in accompanying etymological notes (VT43/30). In The Etymologies of the 1930s, ᴹQ. mitta or minta was glossed “inwards, [?]into” [the second gloss is difficult to read] under the root ᴹ√MI “inside” (EtyAC/MI). In the Qenya Lexicon of the 1910s ,ᴱQ. mitta was glossed “in, into, inwards” under the early root ᴱ√MĪ (QL/61).
Neo-Quenya: For purposes of Neo-Quenya, I would use mitta as a preposition or adverb meaning “inwards, into”, and would assume the 1950s meaning “between” was transient and abandoned.
mitta-
between
mitta- (2) prep. "between" (VT43:30; the final hyphen may suggest that suffixes would normally follow)
neldë
cardinal. three
neldë cardinal "three" (SA:neldor, NÉL-ED, VT47:11, VT48:6). Eleni neldë "three stars", archaic elenion neldë = *"of stars three". Genitive "of 3 stars" = elenion neldë (for archaic elenion neldëo) (VT49:45; see 54 regarding neldion as the gen. pl.) Cf. also nelya, neldëa, Neldië.
olë
cardinal. three
olë (2) cardinal "three" (LT1:258; in LotR-style Quenya Tolkien replaced this "Qenya" form with neldë)
tólë
centre
tólë noun "centre" (LT1:269; the word endë is to be preferred in Tolkien's later Quenya)
A word for “between” in the sense “in the middle” (VT47/11). More precisely it meant “at the central position in a row, list, series, etc. but also applied to the case of three persons” and that it “referred to the position of a thing between others of like kind”, as opposed to imbë used for “between” things of differing kinds. For non-sequential groups Tolkien said enel “was mainly used of persons; from it was derived the word enelmo: ‘a go-between, intervener, intermediary, mediator’ (VT47/14 note #17)”. It was related to the root √ENED “middle” via ancient D/L variations (VT47/31 note #45).