Where does “dortour” come from?

dortour (Middle English) comes from Old French dortoir, from Latin dormitorium, from Latin dormitorius — of or for sleeping.

Ancestry of “dortour”, step by step

Step	Language	Word	Meaning
1	Old French	dortoir	—
2	Latin	dormitorium	a sleeping-room, dormitory
3	Latin	dormitorius	of or for sleeping

dortour — Etymology, Origin & Word History | Etymology Explorer