A root in The Etymologies of the 1930s glossed “void”, with derivatives like ᴹQ. kúma “void” and N. caun “empty” (Ety/KUM). It was probably also the basis of ᴹQ. kumba in ᴹQ. saurikumba in Lord of the Rings drafts from the 1940s, unglossed but probably “✱foul-bellied” (SD/86).
Middle Primitive Elvish
gas
root. yawn, gape
gāsa
noun. void
gassā
noun. hole, gap
syadsē
noun. cleft, gash
kum
root. void
skarwē
noun. wound
tundu
noun. hole
yag
root. yawn, gape
A root in The Etymologies of the 1930s glossed “yawn, gape” with several derivatives such as ᴹQ. assa/N. gas “hole” and N. gaw “void” (Ety/GAS). The names based on this root like N. Belegast and ᴹQ. Ilmen-assa do not appear in later versions of the legendarium, so the eventual fate of this root is uncertain, especially given that there are other roots of similar meaning like ᴹ√YAG “yawn, gape” (Ety/YAG) that do reappear later (Let/383; PE17/35, 42).
Neo-Eldarin: For purposes of Neo-Eldarin, derivatives of this root are among the best attested words for “hole”, so it’s probably best to retain ᴹ√GAS and its derivatives in Neo-Eldarin writing.