násie, interjection amen. The first element could be ná "is" (see na above for references), while #sie may be an abstract formation based on the stem si- this, here, now (LR:385); #sie could then mean "this [situation, matter][24]". Násie must be assumed to have the same meaning as Hebrew `amen, and the latter was used as an affirmative interjection so it is! or that is true! rather than simply optative so be it! It does not necessarily refer to what is merely wished for, but to what is, what is true; Hebrew `amen is indeed related to the word `emeth truth (older *`amint). Interpreting the Quenya word in this light, I tend to conclude that ná-sie is literally [so] is this[25]. (For the fronting of the verb in exclamations, cf. Fingon’s cry before the Nirnaeth Arnoediad: Auta i lómë!, translated the night is passing in the text of Silmarillion Ch. 20, but in the Quenya exclamation the verb auta is passing is placed before its subject.) *Ná sie is then written in one word as a pseudo-interjection násie, but the fact that s does not become z > r, as it regularly does between vowels, gives away that this is not a "genuine" compound. – If násie were to have more strictly optative meaning, so be it! rather than indicative this is so, we might have expected #na be! rather than ná is (see the entry na above regarding the word namárie).
nísiwomen, the nominative plural of níswoman. The plural of nís is also attested in MR:213, but there it appears as nissi instead. Similar, though not wholly identical forms occur in the Etymologies. Under the stem ini- female, a Quenya noun ní female, woman is listed (LR:377). However, in the entry for the stem nî1- woman (of which ini- seems to be a variant with stem-vowel prefixed) it is said that ní was an "archaic and poetic" word only, the current word for woman being rather nis or nisse, pl. nissi in both cases (LR:377). This agrees with the entries nis- (LR:378) and ndis- (LR:375). It is suggested that nis- is an elaboration of nî1- and ini-, while ndis- is in turn a "strengthening" of nis-. In the entry ndis- (LR:375), Tolkien indicates that Q nisse woman comes from primitive ndis-sê. This might seem to indicate that an ending -sê (the precise meaning of which is difficult to pin down) has been added to the stem. On the other hand, we can also understand the primitive form as being *ndiS-ê, the doubling of the s representing a medial fortification; the primitive ending -ê added to this fortified stem would here be feminine. The formation of primitive ndis-sê woman from the stem ndis- is similar to bessê wife from the stem bes- (LR:352). Whatever the precise etymology, in this scenario the Quenya descendant of ndis-sê was nisse, which was apparently normally shortened to nis. This would represent **niss, the final ss being simplified to s since Quenya cannot normally have a double consonant finally; but in the plural form nissi, where the double consonant was not final because of the plural ending, it naturally persists. So far we have discussed the scenario of the Etymologies. As already mentioned, in MR:213 the plural women is still nissi, but in this post-LotR source the singular is given as nís with a long vowel (as if it were influenced by the archaic word ní). The text of the Lord’s Prayer seems to presuppose the same singular, but here the plural is nísi, formed simply by adding the ending -i: there is no hint of any stem-variation. The plural nísi is most surprising, for a single intervocalic s ought to become voiced to z, in turn becoming r. So why do we not see nís woman pl. **nízi/níri just as we have olos dream pl. olozi/olori in UT:396? May Tolkien at this stage have imagined that nís pl. nísi represents earlier *níþ pl. *níþi, since s from earlier þ never becomes z > r? (Cf. for instance nause imagination from older nauþe, LR:378 s.v. nowo-; no form **nauze, **naure arose, evidently because intervocalic s was voiced to z before þ became s; the voicing rule had ceased to function when new s'es developed from þ.) If nís were to represent earlier Quenya *níþ, this would require that the primitive word had a shape quite different from what is suggested in the Etymologies. Whatever the case, the re-emergence of nissi as the plural form in a late source (MR:213) would seem to indicate that Tolkien had changed his mind back again, reviving the plural he had used in the Etymologies. (Hence, writers should probably let the plural of nís be nissi rather than nísi.)
24
According to VT43:24, sie
appears as an
25
Or perhaps rather ná - sie = "[this] is so", if we accept the gloss of sie as "thus"; the meaning remains the same.