Where does “sembilan belas” come from?

sembilan belas (Indonesian) comes from Malay sembilan belas, from Malay belas, from Javanese welas.

sembilan belas (Indonesian): nineteen

Definitions

Step	Language	Word	Meaning
1	Malay	sembilan belas	nineteen
2	Malay	belas	-teen; clemency, pity
3	Javanese	welas	—

sembilan belas — Etymology, Origin & Word History | Etymology Explorer