The root √ANGWA “snake” with variant √ANGU appeared in The Etymologies of the 1930s as the basis for the words ᴹQ. ango “snake” (Ety/ANGWA) and angulóke “dragon” (Ety/LOK). The Noldorin equivalent am- seems to have survived only as a prefix (Ety/ANGWA), and is a good example of how [[on|[ŋgw] > [mb]]] in that language. There are a variety of other words for “snake” in Tolkien’s later writings, so whether this root remained valid is unclear.
Middle Primitive Elvish
am
root. mother
am
root. up
amī̆l
noun. mother
amƀus
noun. breast
ñgyal(am)
root. talk loud or incoherently
tul-
verb. come, am coming, have come, am arrived, am here, are approaching
angwa
root. snake
a
root. intensive prefix
An “intensive” root addition described by Tolkien in The Etymologies from the 1930s (EtyAC/A). It was one of two basic intensive mechanisms, along with the (syllabic) prefixed N- (EtyAC/N). The prefixed vowel a- seems to have been used originally in Primitive Elvish when the base vowel was a, and similarly with E and I (EtyAC/E; Ety/I²); whether this was also true of the vowels o, u is unclear, as Tolkien didn’t mention them. These various vocalic intensifications were frequently accompanied by dynamic lengthening (doubling), with the example given by Tolkien being: ᴹ✶parkā “dry” → ᴹ✶apparkā “very dry, arid” (> N. afarch).
In the case of e- and i-, the examples were dero, dise → ᴹ✶Endero, ᴹ✶Indise “groom, bride”; these examples indicate that other kinds of consonant fortifications were possible, in this case nasalization of stops, which often replaced consonant-doubling for voiced stops in Primitive Elvish.
Specifically in the case of a-, however, it seems it could be used as a general intensive that “was distinct in origin, though similar in function, to the prefixed basic vowel”. Why this was true of a- alone is not clear, but there seems to have been some complex interplay between the vocalic intensives and the intensives derived from syllabic initial ṇ-, with the net result that the intensive prefix in Q. became an-, am-, añ-, depending on the initial consonant.
See the entry on the Quenya comparative for a more detailed discussion of the conceptual development of intensives in Eldarin.
ala-
prefix. very
e
root. intensive prefix
eʒ-
verb. to be
i
root. intensive prefix
ista-
verb. to know
kab-
verb. can, I can
kwentā
noun. tale
mat-
verb. to eat
mbarat
root. fate
wedā
noun. bond
yē
root. to be
ē
root. to be
ī
root. to be
A root in The Etymologies of the 1930s glossed “talk loud or incoherently”, with derivatives like ᴹQ. indyalme “clamour” and N. glamm “barbarous; shouting, confused noise”, the latter serving as the basis for the collective name for Orcs: N. Glamhoth “Barbaric Host” (Ety/GLAM, ÑGAL); this root replace ᴹ√ÑGAL(AM) or ᴹ√ÑYAL(AM) of similar meaning (Ety/ÑGAL; EtyAC/GLAM). In earlier writings, G. Glamhoth was based on glâm “hatred” (GL/39), but in later writings it continued to be translated as “din-horde” or “host of tumult” (UT/39; MR/109; PE17/39), though in the Quendi and Eldar essay S. glam “din, uproar” was derived directly from √(G)LAM “(vocal) sounds that were confused or inarticulate” (WJ/416).
Neo-Eldarin: For purposes of Neo-Eldarin, I think it is worth retaining this root as a (Quenya only?) elaboration of √(G)LAM to salvage ᴹQ. indyalme “clamour”.