A noun appearing as N. thlingril “spider” in The Etymologies, probably a feminine form of N. thling “spider, spider’s web, cobweb” (Ety/SLIG). Christopher Tolkien said the r was uncertain.
Neo-Sindarin: Since initial sl- became lh- in Sindarin, most Neo-Sindarin writers adapt this word as ᴺS. lhingril, as suggested in HSD (HSD). This word is somewhat questionable, since in later writings √ungu- was the basis for spider words (PE22/160). I think ᴹ√SLIG may be reinterpreted as having to do with threads, and as such I think ᴺS. lhingril can be retained as originally meaning “(female) web spinner”. However, I recommend later S. ungol as the more common Sindarin word for “spider”.
A noun appearing as N. thling “spider, spider’s web, cobweb” in The Etymologies, derived from primitive ᴹ✶sliñgē under the root ᴹ√SLIG (Ety/SLIG).
Neo-Sindarin: Since initial sl- became lh- in Sindarin, most Neo-Sindarin writers adapt this word as ᴺS. lhing, as suggested in HSD (HSD). This word is somewhat questionable, since in later writings √ungu- was the basis for spider words (PE22/160). However, I think ᴹ√SLIG may be reinterpreted as having to do with threads, and as such I think ᴺS. lhing can be retained, though I would limit its use to “spider’s web, cobweb”, a synonym of nath “web” but descriptive of more diaphanous webs.