A word in the Declension of Nouns from the early 1930s with stem form hun- and gloss “earth” (QL/39). It might be a later iteration of ᴱQ. han “ground, earth” from the Qenya Lexicon of the 1910s (QL/39), and if so then hún might also be used as “✱ground”. I think it is useful to assume so for purposes of Neo-Quenya, as the other attested word for “ground”, Q. talan, is probably used more often for “floor”, including floors above the ground level.
Qenya
mar-
verb. to abide
mar
noun. home, dwelling, house, habitation; earth
martalmar
place name. Roots of the Earth
ambar
noun. fate
hún
noun. earth, earth, *ground
mar(dar)
adverb. homewards
An “old short allative” form appear in the Declension of Nouns from the early 1930s with suffixal -r, with both monosyllabic mar and longer mardar (PE21/25, 27). Tolkien said the longer for mardar was “less usual” (PE21/27), but it is more distinct from már “home”. This allative variant is probably related to ᴹQ. tar “thither” < ᴹ✶tad from later in the 1930s (Ety/TA; PE19/52).
marta
adverb. home
no
preposition. under
nu
preposition. under
talmar ambaren
place name. Roots of the Earth
The “veins of the world” in some cosmological notes from the 1930s (SM/241-2, 255), also appearing in The Etymologies as combination of mar “world” and the plural of talma “root” (Ety/TAL).