√SAR root. “score, incise; write”
ᴹ√SAR appeared as unglossed root in The Etymologies of the 1930s with derivatives like ᴹQ. sar “(small) stone” and N. sarn “stone as a material” (Ety/SAR). Tolkien use of both these words in later writings in names like Q. Elessar “Elfstone” (LotR/375) and S. Sarn Athrad “Ford of Stones” (S/92) indicates the ongoing validatity of this meaning, though in later writings S. sarn also = “pebble, small stone” (RC/327; VT42/11).
However, in the Quendi and Eldar essay of 1959-60, Tolkien gave a different meaning for this root as √SAR “score, incise”, from which it developed the extended sense “write” and became the basis for the name of the first alphabet of the Elves, the Q. sarati (WJ/396). This use ᴱQ. sar- as “write” dates back to Early Qenya Word-lists of the 1920s (PE16/133). Despite the difference in meaning, I think two root could still be essentially the same, with √SAR = “stone” as a noun and √SAR = “score (stone)” as a verb, and from there eventually developing the sense “write” to serve as the basis for sarati. In one place in the Quendi and Eldar Tolkien revised √SAR >> √SYAR, perhaps indicating he considered making √SYAR an etymological variant of √SAR (WJ/419 note #24).
References ✧ WJ/396, 419
ᴹ√SAR root. “*stone”
References ✧ Ety/SAR, STAR