√MBON root. “*lump, mass”
In a discussion of the comparative written around 1967, Tolkien proposed two new roots to serve as the basis for Q. ambo and S. amon “hill”, first √MAB “lump, mass” > Q. ambo (PE17/90), then √MBŎNO [unglossed] > S. amon, with the Q. form being umbo(n) “hill, lump, clump, mass”, the latter attested nowhere else (PE17/93). Elsewhere “hill” words were typically derived from √AM “up” (PE17/92; Ety/AM²), and Tolkien’s decision to introduce new roots for hill words was probably motivatived by his decision in these 1967 comparative notes to make √AMA = “addition, increase, plus” be the basis for the comparative (PE17/91).
Neo-Eldarin: For purposes of Neo-Eldarin, I prefer to assume the comparative is based instead on an-, but √MBON “*lump, mass” may be worth retaining as an additional influence for hill words.
References ✧ PE17/93, 165