Where does “-st” come from?

-st (Hungarian) comes from Hungarian -t, from Proto-Uralic -tt.

Ancestry of “-st”, step by step

Step	Language	Word	Meaning
1	Hungarian	-t	Used to form the accusative case; -ed, -t. Used...
2	Proto-Uralic	-tt	—

-st — Etymology, Origin & Word History | Etymology Explorer