An adjective appearing as N. flaew “sickly, sick, ill” in The Etymologies of the 1930s derived from ON. thlaiwa < ᴹ✶slaiwā under the root ᴹ√SLIW “sickly” (Ety/SLIW). The ancient initial <em>sl</em> became <em>thl</em> which was the usual sound change in (Old) Noldorin, and then this <em>thl</em> became <em>fl</em>, a less common Noldorin sound change. Tolkien wrote an intermediate form thlaew between ON. thlaiwa and N. flaew, but then revised this form to thloew, reflecting some uncertainty on the phonetic development of <em>ai</em> in Noldorin. There was also a deleted variant of this root: ᴹ√LIW, where Tolkien had lhaew “ill” with the usual unvoicing of initial <em>l</em> in Noldorin (EtyAC/LIW).
Neo-Sindarin: In Sindarin of the 1950s and 60s, initial <em>sl</em> became <em>lh</em> instead of thl, so most Neo-Sindarin writers adapt this word as ᴺS. lhaew “sickly, sick, ill”, as suggested by HSD (HSD).
The Etymologies of the 1930s had N. lhaew “frequent, many” derived from primitive ᴹ✶lai- which was an a-fortified form of the root ᴹ√LI “many” (EtyAC/LI).
Neo-Sindarin: Many Neo-Sindarin writers adapt this word as ᴺS. laew “great number” for purposes of Neo-Sindarin as suggested in HSD (HSD), since the unvoicing of initial <em>l</em> to <em>lh</em> was a feature of Noldorin of the 1930s but not Sindarin of the 1950s and 60s.
Conceptual Development: The Gnomish Lexicon of the 1910s had G. odrim “(very) many” related to G. odog “mighty, great; violent, excessive, exceeding; very” (GL/62).