Where does “fak” come from?

fak (Old Frisian) comes from Proto-Germanic faką, from Proto-Indo-European peh₂ǵ- — to attach.

Ancestry of “fak”, step by step

StepLanguageWordMeaning
1Proto-GermanicfakąAn enclosed or defined space; division;...
2Proto-Indo-Europeanpeh₂ǵ-to attach
Every word from Proto-Indo-European peh₂ǵ- →Every word from Proto-Germanic faką →