Where does “पौष” come from?

पौष (Sanskrit) comes from Sanskrit पुष्य, from Sanskrit पुष्, from Proto-Indo-European *(h₃)pews-.

Ancestry of “पौष”, step by step

Step	Language	Word	Meaning
1	Sanskrit	पुष्य	—
2	Sanskrit	पुष्	to be nourished, to thrive, flourish, prosper
3	Proto-Indo-European	*(h₃)pews-	—

पौष — Etymology, Origin & Word History | Etymology Explorer