Where does “মৃত্যু” come from?

মৃত্যু (Bengali) comes from Sanskrit मृत्यु, from Sanskrit मृ, from Proto-Indo-Iranian *mar-.

মৃত্যু (Bengali): death

Definitions

Step	Language	Word	Meaning
1	Sanskrit	मृत्यु	death, dying; Death personified, the god of...
2	Sanskrit	मृ	to die
3	Proto-Indo-Iranian	*mar-	—

মৃত্যু — Etymology, Origin & Word History | Etymology Explorer