The basic word for “stone” or “rock” in Sindarin (PE17/28-29; WJ/201). More specifically, it was “stone as a material” (PE17/28; Ety/GOND) as opposed to an individual stone, which was S. sarn (RC/327; VT42/11). In one place Tolkien said “Sindarin had a short form gŏn- < ✱PQ gōn, gon-, stone, a stone, or a single thing made of stone” (PE17/28), and in another Tolkien said “shorter gon- was used for smaller objects made of stone, especially carved figures” (RC/347); this short form seems to be prefixal. Longer gond was derived from the root ᴹ√GONOD of essentially the same meaning, as was its Quenya cognate Q. ondo (Ety/GOND).
Conceptual Development: This word dates all the way back to the Gnomish Lexicon of the 1910s where this word appeared as G. gonn “great stone, rock” (GL/41). It was probably a derivative of ᴱ√ONO “hard” from the contemporaneous Qenya Lexicon from which its Qenya cognate ᴱQ. on(d) “a stone” was derived (QL/70). The early root form was probably ✱ᴱ√ƷONO, with the initial ʒ vanishing in Qenya but becoming g in Gnomish. Later on, this derivation no longer worked, since Tolkien decided that initial ʒ became h in Qenya. In The Etymologies of the 1930s, this word appeared as N. gonn “stone (as a material)” with the derivation given above (Ety/GOND).
Neo-Sindarin: Tolkien gave this word as both gonn and gond, but in keeping with the notion that the sound “remained nd at the end of fully accented monosyllables” in Sindarin (LotR/1115), most Neo-Sindarin writers use gond.
_n. _stone, rock. Archaic S. gond > gonn. Q. ondo. >> Gondor