ممنون

ممنون is borrowed from Arabic مَمْنُون, the passive participle of the root م ن ن ("to favor, to bestow"). The literal sense is "one who has been favored," and Persian softened that obligation into a polite reflex. Foreigners often default to مرسی because it feels easy, but Iranians notice when you reach for ممنون instead. It signals you have moved past tourist Persian. Pair it with دستت درد نکنه ("may your hand not hurt") and you have the full courteous package any host or shopkeeper expects.