From Proto-Tai *wɤjᴬ (“fire”). Cognate with Thai ไฟ (fai), Northern Thai ᨼᩱ (fai), Lao ໄຟ (fai), Lü ᦺᦝ (fay), Tai Dam ꪼꪡ, Shan ၽႆး (phái) or ၾႆး (fái), Zhuang feiz, Bouyei fix, Saek วี๊.
ᥜᥭᥰ (fäy) (1963 orthography ᥜᥭ̈)