Where does “soilen” come from?

soilen (Middle English) comes from Old French soillier, from Frankish *sulwijan, from Proto-Germanic sulwijaną, from Proto-Indo-European sūl- — thick liquid, muck.

Ancestry of “soilen”, step by step

StepLanguageWordMeaning
1Old FrenchsoillierAlternative form of souillier; to soil
2Frankish*sulwijan—
3Proto-Germanicsulwijanąto make dirty; to sully
4Proto-Indo-Europeansūl-thick liquid, muck
Every word from Proto-Indo-European sūl- →Every word from Proto-Germanic sulwijaną →Every word from Frankish *sulwijan →