MFN, at least, is a standard and common term-of-art in contracts and can apply to all kinds of things where a party wants to guarantee that no one else gets a better deal.

> is a standard and common term-of-art in contracts

the reason this isn't exactly helpful is because everyone says that about everything contract related. thats the user experience of being presented a contract whether it is true or not.

got a list? is there a document on clause etymology?

I'm pretty sure that the "most favored nation" term goes back to international tariffs.

Among the nations your nation trades with, some are your "customs buddies" (not a real term :-)), for whatever reason -- there's a lot of reciprocal trade, you're allies in war, the other nation is scary enough to shake you down... Those nations get lower customs rates. The nations that get the best rates are the "most favored nations". When countries negotiate new trade agreements, a common demand is for "most favored nation status", i.e., that you won't charge them any more than the lowest rate you charge the "most favored" country.

is there a list or document on clause etymology?

its not really about just the MFN explanation anymore, thanks for the one potential synopsis on that particular concept