Where does “Nebenprodukt” come from?

Nebenprodukt (German) comes from German Produkt, from Latin productum, from Latin prōdūcere.

Nebenprodukt (German): by-product

Definitions

Step	Language	Word	Meaning
1	German	Produkt	product
2	Latin	productum	that which is brought forward or produced;...
3	Latin	prōdūcere	—

Nebenprodukt — Etymology, Origin & Word History | Etymology Explorer