Where does “tor” come from?

tor (Middle English) comes from Old English torr, from Latin Turris, from Ancient Greek τύρρις, from Ancient Greek τύρσις — tower, bastion.

Ancestry of “tor”, step by step

Step	Language	Word	Meaning
1	Old English	torr	tower
2	Latin	Turris	A river of Venetia, now called Torre
3	Ancient Greek	τύρρις	tower, walled city
4	Ancient Greek	τύρσις	tower, bastion