nís (niss-, as in pl. nissi) noun "woman" _(MR:213. The Etymologies gives _nis (or nissë), pl. nissi: see the stems NDIS-SĒ/SĀ, NI1, NIS (NĒR), VT46:4; compare VT47:33. In Tolkien's Quenya rendering of Hail Mary, the plural nísi occurs instead of nissi; this form is curious, since nísi would be expected to turn into *nízi, *_níri** (VT43:31). VT47:33 suggests that Tolkien at one point considered _niþ- as the older form of the stem, which etymology would solve this problem (since s from older þ does not become z > r). Even so, the MR forms, nís with stem niss-, may be preferred. - Compare †ní, #nína, nisto, Lindissë.
Quenya
nis-
verb. *to smell sweetly
nís
noun. woman (of any kindred: elf, human or dwarf)
nís
woman
Lindissë
woman
Lindissë fem.name, perhaps lin- (root of words having to do with song/music) + (n)dissë "woman" (see nís). (UT:210)
ni
me
ni (1) 1st person sg. pron. "I" (according to PE17:68 also "me" as object), with long vowel (ní) when stressed (VT49:51), cf. ní nauva next to nauvan for "I will be" (VT49:19), the former wording emphasizing the pronoun. The pronoun ni represents the original stem-form (VT49:50). Dative nin "for me, to me" (Arct, Nam, RGEO:67, VT41:11/15). Compare the reflexive pronoun imni, imnë "myself" and the emphatic pronoun inyë, q.v. The ancient element ni is said to have implied, originally, "this by me, of my [?concern]" (VT49:37)
nissë
woman
nissë noun "woman" (NDIS-SĒ/SĀ, NI1, NIS, VT47:33); see nís. Note: nissë could apparently also mean "in me", the locative form of the 1st person pronoun ni, q.v.
nissë
noun. woman
ní
woman, female
†ní (2) noun "woman, female" (NI1, INI (NĒR ) ). Not to be confused with ní as a stressed form of the pronoun ni "I".
nína
woman
#nína (gen.pl. nínaron attested) noun "woman" (VT43:31; this word, as well as some other experimental forms listed in the same source, seem ephemeral: several sources agree that the Quenya word for "woman" is nís, nis [q.v.])
wenci
woman, maiden
wenci ("k") noun, apparently a diminutive form of the stem wēn- "woman, maiden". It is possible that this is meant to be Common Eldarin rather than Quenya; if so the Quenya form would be *wencë (compare nercë "little man") (VT48:18)
The usual Quenya word for “woman” or more exactly a “female person” of any kindred (PE23/87), in later writings appearing as both nís (MR/213, 226, 229) and nisse (VT47/18, 33). Even in the cases where its singular was nís, its plural form was given as nissi, indicating a stem form of niss-. In rough notes from 1968 Tolkien said “The monosyllabic nouns (especially those with only one stem-consonant) were a small dwindling class often replaced by strengthened forms (as nis- was [by] nisse)” (VT47/18).
Thus it seems the ancient form was ✱nis- from the root √NIS, which like its male counterpart Q. nér “man” inherited a long vowel from the ancient subjective form ✱nīs. But the voiceless s was felt to be intrinsic to word, and it was thus strengthened to niss- in inflected forms to avoid the sound changes associated with an isolated s. From this a longer form nisse was generalized. In practice I think either form can be used, with singular nís being preserved by analogy with nér. However, I think inflected forms are probably all based on nisse, such as genitive nisseo “of a woman” rather than ✱✱nisso.
Conceptual Development: In The Etymologies of the 1930s Tolkien had both ᴹQ. nis and nisse “woman” derived from the root ᴹ√NIS, with plural nissi in both cases (Ety/NIS, NDIS). He explained this variation as follows: “nis was a blend of old nīs (nisen) and the elab[orated] form ✱nis-sē” (EtyAC/NĪ¹). Hence it is was essentially the same as the scenario described above, but in the 1930s the long vowel in ancient nīs did not survive in the later short form nis. Quenya Personal Pronouns (QPP1) from the late 1940s had nís “woman” with a long í (PE23/85).
In Quenya prayers of the 1950s, Tolkien experimented with some alternate plural forms nínaron [genitive plural] >> nísi [ordinary plural] (VT43/26-29, 31), the former apparently representing a variant singular form ✱nína, but in later writings plural nissi was restored.