An unglossed root in The Etymologies of the 1930s serving as the basis for the word ᴹQ. malle “street” and ᴹQ. ambal “shaped stone, flag”, the second gloss probably meaning “flag stone” (Ety/MBAL). In the the Qenya Lexicon of the 1910s, the strengthened root ᴱ√MBALA was glossed “crush, hurt, pain, damage, give maim to” with Gnomish variant bal- and derivatives like ᴱQ. maldor “agony” and G. bal “anguish, pain” (QL/58; GL/21); the root entry is given under ᴱ√MALA³, but a list of roots at the end of the M-section make it clear the strengthened root is in fact ᴱ√MBALA (QL/63).
The Qenya Lexicon also has an unstrengthened root ᴱ√MALA “crush, squeeze, pulp” to which ᴱ√MBALA was related, whose derivatives include ᴱQ. mal- “to crush”, ᴱQ. malle “street” and G. mal “paved way, road” (QL/58; GL/56). There was another variant root ᴱ√MLŘL [MḶÐḶ] “crush, pound”, also connected to ᴱ√MALA¹ and with Gnomish variant blid[h]-, though it had no obvious derivatives in the contemporaneous Gnomish Lexicon (QL/62-63). In the The Etymologies of the 1930s, it seems the “torment” words were transferred to ᴹ√(Ñ)GWAL: in the 1910s it seems in initial element of G. Balrog was from ᴱ√MBALA (GL/21; LT1A/Balrog) but in the 1930s it was from N. baul “torment” < ᴹ√(Ñ)GWAL (Ety/ÑGWAL). Thus 1930s ᴹ√MBAL was probably limited to meanings like “*crush, pound”.