Where does “पृथक” come from?

पृथक (Hindi) comes from Sanskrit पृथक्, from Sanskrit प्रथ्, from Proto-Indo-European pleth₂- — flat.

पृथक (Hindi): separate, disjoint; different

Definitions

Step	Language	Word	Meaning
1	Sanskrit	पृथक्	—
2	Sanskrit	प्रथ्	—
3	Proto-Indo-European	pleth₂-	flat

पृथक — Etymology, Origin & Word History | Etymology Explorer