A noun in The Etymologies of the 1930s glossed “spider” derived from the root ᴹ√SLIG with various other derivatives having to do with webs and fine threads (Ety/SLIG). Most notably it was the second element in the name ᴹQ. Ungoliante “Gloomweaver” (LR/230). In the paradigm of The Etymologies, ᴹQ. ungo was “cloud, dark shadow” (Ety/UÑG), not “spider”.
Conceptual Development: In the Qenya Lexicon and Poetic and Mythological Words of Eldarissa of the 1910s, ᴱQ. liante was glossed “tendril” and was derived from the early root ᴱ√LI+ya “unite many in one” (QL/53, PME/53). In this period it was an element in the name ᴱQ. Ungweliante or Ungwe Lianti “the great spider who enmeshes” (LT1/152), where the intial element ᴱQ. ungwe meant “spider” (QL/98). In the Early Qenya Grammar of the 1920s, ᴱQ. liante was translated “vine” (PE14/55), as opposed to the Qenya Lexicon of the 1910s where ᴱQ. liantasse was “vine” (QL/53).
Neo-Quenya: Tolkien gave no other Quenya words for “spider” in his later writings, but S. ungol was glossed “spider” (Let/180; RC/490, 767) and √ungu- was described as the basis for “spider words” (PE22/160), making it very likely that ✱ungol was “spider” in his later conception of the name Q. Ungoliantë. However, I think [ᴹQ.] liante might be reconceived of as a (feminine?) agental form originally meaning “weaver” or “webspinner”. Furthermore, I think [ᴺQ.] ungol might have come to be associated only with monstrous spiders, the descendants of Ungoliantë, so that [ᴹQ.] liante came to be used of ordinary spiders.
The correlative ᴹQ. indon “as” appeared in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/111), a combination of the relative pronoun ᴹQ. i and the similative suffix ᴹQ. -ndon.