Where does “مَرْسِين” come from?

مَرْسِين (Arabic) comes from Ancient Greek μυρσίνη, from Ancient Greek μῠ́ρτος — myrtle (Myrtus communis).

Ancestry of “مَرْسِين”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	μυρσίνη	myrtle (Myrtus communis)
2	Ancient Greek	μῠ́ρτος	myrtle (Myrtus communis)