*aflaz

Uncertain. Kroonen (2013: 3) posits the derivation from a thematicized reflex of a Proto-Indo-European amphikinetic l/n-stem *h₂épōl ~ *h₂épl̥, genitive *h₂p-n-ós (‘fire pit, hearth’), comparing it with Hittite 𒄩𒀊𒁉𒈾𒀸 (ḫa-ap-pé-na-aš /ḫappenaš/). But the Hittite form may alternatively belong to a separate derivative, *h₃op-en-o- from the root *h₃ep-, comparable with Ancient Greek ὀπτός (optós) and ὀπτάω (optáō,) (Puhvel 1991: 121–22), in which case the direct l/n-stem comparison is less secure. (Wachter (1997) gives good reason to doubt the existence of an l/n heteroclite class.) A substrate or technical Wanderwort origin is also possible.