Where does “грузи́ть” come from?

грузи́ть (Russian) comes from Proto-Slavic groziti, from Proto-Balto-Slavic graź-.

Ancestry of “грузи́ть”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	groziti	to threaten
2	Proto-Balto-Slavic	graź-	—