Where does “पुष्पक” come from?

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

पुष्पक (Sanskrit): flowery

Definitions

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

पुष्पक — Etymology, Origin & Word History | Etymology Explorer