If America wasn't bizarrely and undeservedly named for Amerigo Vespucci, what could its current name be? Probably Columbia, but another very real possibility is Occidentalia, by analogy with how Australia got named some centuries later. Of course this word would have long ago been shortened to Oxy in English.
This would have probably led "oxymoron" to be so hopelessly politicized by now that another word would have had to be found to express its original meaning. Or maybe not - after an initial period of confusion Americans could have reclaimed "oxymoron" with pride. If you think about it, it can suggest that calling Oxies morons is oxymoronic, i.e. uncalled for.