A noun in the Gnomish Lexicon of the 1910s glossed “an incline, slope” (GL/61), probably a derivative of the root ᴱ√NUHU “bow, bend down, stoop, sink” as suggested by Christopher Tolkien (LT1A/Númë; QL/68).
Gnomish
inc
adjective. little
inco
pronoun. the same, the identical
nacthanaith
noun. incisor (tooth)
numbros
noun. incline, slope
gam(m)a-
verb. to gain, profit, increase; to be profitable, bring in revenue
intha-
verb. to join to (intr.), add, increase, add to
gintha-
verb. to join to (intr.), add, increase, add to
nud-
verb. to incline head, bend face down
inig
adjective. small
aina
adjective. small
ineg
adjective. small
migin
adjective. little
odra
adverb. very
A noun appearing as G. nacthanaith “incisor (tooth)” in the Gnomish Lexicon of the 1910s, a combination of G. nactha- “bite” and G. naith “tooth” (GL/41).
Neo-Sindarin: I would adapt this as ᴺS. nagnel “incisor” for purposes of Neo-Sindarin, using the later word [N.] nêl for “tooth”, and with the initial element [N.] nag- “bite”.