ᴹ√KUM root. “void”
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).
References ✧ Ety/AWA, KUM