Where does “though” come from?

Though comes from Old English þēah, a conjunction expressing concession or contrast whose original sense remains uncertain.

though (English): Despite that; however; Used to intensify...

Definitions

Step	Language	Word	Meaning
1	Middle English	thogh	Alternative form of þou; though
2	Old English	þēah	though, although, even if, that, however,...

though — Etymology, Origin & Word History | Etymology Explorer