Where does “toom” come from?

toom (Middle English) comes from Old English tōm, from Proto-Germanic tōmaz, from Proto-Indo-European doma- — to tame.

Ancestry of “toom”, step by step

Step	Language	Word	Meaning
1	Old English	tōm	empty
2	Proto-Germanic	tōmaz	free, clear, empty, unoccupied
3	Proto-Indo-European	doma-	to tame

toom — Etymology, Origin & Word History | Etymology Explorer