Where does “fec” come from?

fec (Middle English) comes from Old English fæc, from Proto-West Germanic fak, from Proto-Germanic faką, from Proto-Indo-European peh₂ǵ- — to attach.

Ancestry of “fec”, step by step

Step	Language	Word	Meaning
1	Old English	fæc	a division, space; a portion, period, or space of...
2	Proto-West Germanic	fak	division, compartment; period, interval
3	Proto-Germanic	faką	An enclosed or defined space; division;...
4	Proto-Indo-European	peh₂ǵ-	to attach

fec — Etymology, Origin & Word History | Etymology Explorer