A word for “cave, mine, underground dwelling” in Notes on Names (NN) from 1957, derived from the root √PHELEK, that Tolkien considered as an alternative to fela (< ✶phelgā) for the initial element of the name Felagund (PE17/118).

Conceptual Development: N. feleg “(animal’s) horn; steep mountain peak” appeared in a deleted entry in The Etymologies of the 1930s, but that seems unrelated.

Neo-Sindarin: In a note from 1959, Tolkien derived Felagund as a loan word from Khuzdul Felakgundu “Cave Hewer” (PM/352), and this was the etymology Christopher Tolkien gave in The Silmarillion index (SI/Felagund). I prefer this as the basis for Felagund’s name, and √PHELEG over √PHELEK as the ancient Elvish root. Nevertheless I think feleg “cave” may remain viable in Neo-Sindarin as a loan word from Khuzdul. The similarity of ancient Elvish PHELEG and Dwarvish radical *F-L-K may be a coincidence or the result of Avari influence on Ancient Dwarvish.

A deleted word in The Etymologies of the 1930s, the only derivative of the deleted root ᴹ√PHELEK “(animal’s) horn; steep mountain peak” and thus probably of similar meaning (EtyAC/PHELÉK). In later writings, S. feleg was a word for “cave”.