Acronym for most favored nation rights. A trade law term that refers to the language used in freedom, commerce, and navigation agreement (FCN) under which countries agree to trade with one another. Most favored nation usually means that trade with that country will attract the lowest possible tariff and other trade terms applied to any other trading country. All parties to the General Agreement on Tariffs and Trade (the GATT) are obliged under to apply MFN treatment to one another under Article I of the GATT.