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).
Gnomish
sarn
noun. a stone
sarnathrod
place name. Stony Ford
sard
noun. table
dal
noun. cairn
clochiol
adjective. stone
clocthi
noun. pebble
A noun for “a pebble” in the Gnomish Lexicon of the 1910s, apparently a diminutive of G. cloch “a stone” (GL/26).
closs
noun. shingle
A word for “shingle” in the Gnomish Lexicon of the 1910s, related to G. clog or cloch “a stone” and thus probably with the sense “mass of pebbles” (shingle bank) rather than “roof tile” (GL/26).
gond
noun. stone
A noun appearing as G. sard “table” in the Gnomish Lexicon of the 1910s, which Tolkien compared to G. thrad “plank” (GL/67, 73). It was likely based on the early root ᴱ√SARA from the contemporaneous Qenya Lexicon having to do with sawing and sawed things like planks (QL/82). However, elsewhere in Gnomish Lexicon Tolkien had G. thar- “ to saw (up)” indicating a variant or revised root ᴱ√ÞARA (GL/72).
Neo-Sindarin: For purposes of Neo-Sindarin, I would assume the verbal sense of thar- “to saw” might still be viable as related to the later root √THAR “✱across” (referring to a sawing motion). From this I would adapt the Gnomish word for “table” as ᴺS. sardh, where the final rd became rdh as with words like gardh, and the initial s is due to dissimilation of th away from the final spirant dh; compare to úsaeth a deleted variant of úthaes (VT44/30).