An adjectival form of li(n)-, translated “(not) a few, several” and appearing in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/106). Tolkien said “this is rare, since this notion is expressed by the ‘long plural’ in –li: Eldali, Elves, some Elves, several Elves”. In drafts Tolkien said it could also mean “lines (straight or string)” (PE23/106 note #80), probably an allusion to ᴹQ. lia “fine thread, spider filament” from The Etymologies (Ety/SLIG).
Conceptual Development: The Qenya Lexicon of the 1910s had ᴱQ. lia(r) “many” based on the early root ᴱ√LĪ (QL/53).
Neo-Quenya: For purposes of Neo-Quenya, I would use the adjective lia for an indefinite but moderately sized number = “several”, but not a large number for which I use rimba “✱many” or a very small one for which I use sempa “few”. As noted above, it can usually be replaced by the partitive plural suffix -li.
A noun in The Etymologies of the 1930s glossed “fine thread, spider filament” and derived from ᴹ✶ligā under the root ᴹ√SLIG having to do with spider words (Ety/SLIG). In drafts of Demonstrative, Relative, and Correlative Stems (DRC) from 1948, Tolkien gave a second hard-to-read gloss after ᴹQ. lia “many” which might read “lines (straight or string)”, with “string” deleted (PE23/106 note #80); this was probably an allusion to the noun derived from ᴹ√SLIG.
Conceptual Development: The word ᴱQ. lia “twine” appeared in the Qenya Lexicon of the 1910s under the early root ᴱ√LI+ya “unite many as one” with derivatives having to do with threads and vines (QL/53).
Neo-Quenya: In Tolkien’s later writings, √ungu- became the basis for spider words, but I retain ᴹ√SLIG assuming it has to do with threads and strings to salvage words from the 1910s and 30s. As such I’d use lia for threads and strings that are relatively thin compared to other items of their class, especially those crafted by twining: “fine thread”, a “twine” as a thin cord and by extension things like a “✱wire”. I would also use it for “line” but not necessarily one that is straight, such as in a line in a drawing.