A noun in Quenya Notes from 1957 (QN) with variants hlóke and lóke based on primitive ✶(s)lōkō “reptile, snake, worm” from the root √LOK “bend, loop”, so presumably having a similar meaning (PE17/160). Christopher Tolkien also had (h)lóke in The Silmarillion appendix, but gave it the glosses “snake, serpent” (SA/lok). Its Sindarin cognate lhûg points towards a Quenya form hlócë.
Conceptual Development: ᴱQ. lóke (lóki-) “snake” appeared all the way back in the Qenya Lexicon of the 1910s under the early root ᴱ√LOKO “twine, twist, curl” (QL/55). It was also mentioned with the gloss “snake” in the Official Name List for the Lost Tales (PE13/105) and the Name-list to the Fall of Gondolin (PE15/28). It appeared in the contemporaneous Gnomish Lexicon as related to G. ulug “dragon” (GL/74), and in The Lost Tales proper lóke was given as the “the Eldar name [of] the worms of Melko”, that is dragons (LT1/85).
In The Etymologies of the 1930s, Tolkien glossed ᴹQ. lóke as “dragon” under the root ᴹ√LOK “great serpent, dragon” along with Noldorin cognate N. lhûg (Ety/LOK). It was followed by an -ī in parenthesis, indicating a primitive form of ✱lōkī and a stem form of lóki-. Tolkien’s vacillation on its 1957 form was probably out of a desire to retain lhûg as the Sindarin form. In Noldorin of the 1930s an initial l was unvoiced to lh, but this was no longer true of Sindarin of the 1950s and 60s, so Sindarin lhûg required a corresponding Quenya form of hlócë.
Neo-Quenya: For purposes of Neo-Quenya, I recommend sticking with hlócë. Furthermore, since this Quenya word cannot be derived directly from ✶(s)lōkō, I would assume a primitive form slōkī and a stem form hlóci- compatible with its earlier appearances. Given the breadth of its glosses, I would assume the word can apply to any sinuous reptilian creature with or without legs, including lizards, snakes and dragons.
hlócë ("k")noun "snake, serpent", later lócë ("k")(SA:lok-)