A word in the Gnomish Lexicon of the 1910s given as {gondriol “rock”} >> gonwen “rocky”, an adjectival form of G. gonn “great stone, rock” (GL/41).
Gnomish
gonn
noun. (great) stone, rock
gond
noun. stone
gontha
noun. pillar, stele, memorial
gonwed
adjective. rocky
gonthos
noun. great rock
The noun G. {gondos >>} gonthos “great rock” appeared in the Gnomish Lexicon, apparently a variant of G. gontha “pillar, stele, memorial” (GL/41).
Neo-Sindarin: I think the deleted Gnomish form can be adapted into Neo-Sindarin as ᴺS. gonnos, a combination of S. gond “stone” and the variant -os of the augmentative suffix S. -oth.
gondolin
place name. Stone of Song
gondothlimbar
place name. City of the Dwellers in Stone, Dwelling of the Folk of Stone
clochiol
adjective. stone
An adjective for “stone” in the Gnomish Lexicon of the 1910s appearing as an element in G. gôf·clochiol “stone-fruit” (GL/40), derived from G. cloch “a stone” (GL/26).
taul
noun. pillar
A noun appearing as G. gontha- “a pillar, stele, memorial” in the Gnomish Lexicon of the 1910s, an elaboration of G. gonn “stone” (GL/41). The reason for the “-” at the end of the word is unclear. This word was originally G. gontha- “boy”.
Neo-Sindarin: For purposes of Neo-Sindarin I would update this word to ᴺS. gonnoth “pillar, stele, memorial” with the augmentative suffix -oth, so originally “✱great stone”.