Where does “bontsd” come from?

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

Ancestry of “bontsd”, step by step

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