Where does “sittende” come from?

sittende (Middle English) comes from Old English sittende, from Proto-Germanic sitjandz, from Proto-Germanic sitjaną, from Proto-Indo-European sḗd-.

Ancestry of “sittende”, step by step

Step	Language	Word	Meaning
1	Old English	sittende	sitting
2	Proto-Germanic	sitjandz	sitting
3	Proto-Germanic	sitjaną	to sit
4	Proto-Indo-European	sḗd-	—

sittende — Etymology, Origin & Word History | Etymology Explorer