In international economic relations and international politics, most favoured nation (MFN) is a status or level of treatment accorded by one state to another in international trade. The term means the country which is the recipient of this treatment must nominally receive equal trade advantages as the "most favoured nation" by the country granting such treatment. In effect, a country that has been accorded MFN status may not be treated less advantageously than any other country with MFN status by the promising country.
Trump's US drug prices order: what is Most Favoured Nation status?
The president promises sweeping price cuts "almost immediately", but experts say these are unlikely.
BBC News