The Americas are quite a bit larger than the USA, so I disagree with 'american' being a word for people and things from mainland USA. Usian seems like a reasonable derivative of USA and US, similar to how mexican follows from Mexico and Estados Unidos Mexicanos.
The Americas are quite a bit larger than the USA, so I disagree with 'american' being a word for people and things from mainland USA. Usian seems like a reasonable derivative of USA and US, similar to how mexican follows from Mexico and Estados Unidos Mexicanos.