Where does “Isnin” come from?

Isnin (Malay) comes from Classical Malay اثنين, from Arabic الاِثْنَيْن, from Arabic اِثْنَان — two.

Ancestry of “Isnin”, step by step

Step	Language	Word	Meaning
1	Classical Malay	اثنين	—
2	Arabic	الاِثْنَيْن	—
3	Arabic	اِثْنَان	two

Isnin — Etymology, Origin & Word History | Etymology Explorer