Where does “dros” come from?

dros (Middle English) comes from Old English drōs, from Proto-Germanic drōhs, from Proto-Indo-European dʰrā́ks — dregs, sediment.

Ancestry of “dros”, step by step

StepLanguageWordMeaning
1Old Englishdrōs—
2Proto-Germanicdrōhsdregs, sediment
3Proto-Indo-Europeandʰrā́ksdregs, sediment
Every word from Proto-Indo-European dʰrā́ks →Every word from Proto-Germanic drōhs →Every word from Old English drōs →