N. fliw n. “sickness” (Category: Sick; Sickness)
A noun appearing as N. fliw “sickness” in The Etymologies of the 1930s derived from ON. thlīwe < ᴹ✶slīwē under the root ᴹ√SLIW “sickly” (Ety/SLIW). The ancient initial sl became thl which was the usual sound change in (Old) Noldorin, and then this thl became fl, a less common Noldorin sound change. There was also a deleted variant of this root: ᴹ√LIW, where Tolkien had lhîw “disease” with the usual unvoicing of initial l in Noldorin (EtyAC/LIW).
Neo-Sindarin: In Sindarin of the 1950s and 60s, initial sl became lh instead of thl, so most Neo-Sindarin writers adapt this word as ᴺS. lhîw, as suggested by Hiswelókë’s Sindarin Dictionary (HSD). Based on the deleted variant of the root, I would use the word lhîw for both “sickness” and “disease”, both within a body and independent of it.
References ✧ Ety/SLIW; EtyAC/LIW
|ON. thlīwe > thliw > fliw||[θlīwe] > [θlīw] > [θliw] > [fliw]||✧ Ety/SLIW|