13th cent. From Latin fel 'id.,' from an unattested pre-form *fell (perhaps under influence from mel "honey").
From Proto-Italic *fell "bile," "yellow." The word is a bit of a "Italic" mystery. The appurtanance of *f- in Proto-Italic points to *gwh- or *bh- in Proto-Indo-European, yet in all other languages we see signs the original sound was *ǵh-. One "solution" proposed is that one of the dialects within Italic underwent a sound change *ǵh to *f; while the dialect did not survive, the word *fell managed to outlive the dialect and replaced the native word (de Vaan 2014). As one can see, this proposal is hardly convincing; yet linguists are left without a better explanation. Therefore, the assumed proto-form in Indo-European is *ǵhelh3-n̥- "yellow."
Asturian fiel, Portuguese fel, Catalan fel, French fiel, Italian fiele, Aromanian heari, Romanian fiere, Sardinian febi, fele
Old Norse gall "gall," Old High German galla 'id.,' Old Saxon galla 'id.,' Old English gealla 'id.' (English gall)
Old Church Slavonic zlьčь "bile," Russian žëlč' 'id.,' Czech žluč 'id.,' Bulgarian zlăč 'id.,' Lithuanian tulžìs 'id.,' Latvian žul̂(k)ts 'id.'
Ancient Greek χόλος (khólos) "bile," "wrath"
Avestan zāra- "bile"