A noun appearing as G. fafli “a bladder” in the Gnomish Lexicon of the 1910s, an elaboration of G. faf- “puff, blow” (GL/33).

Neo-Sindarin: I would adapt this word as ᴺS. faul “bladder” from ᴺS. faw- “puff, blow”, likely with the original sense “inflated thing”. This mirrors the etymology of English “bladder”, which is also derived from an ancient verb meaning “to blow”.