"non-native", as in descendant of more or less recent immigrants. The opposite is authochtonous, which means native and was the word i actually wanted to use - i'm Euro, so being a mayo means being native, not being a settler. I guess it's mostly superfluous, Amerikans today regard all white citizens as part of the in-group, but Euros are weird in that regard and it makes some sense to differentiate between the native white population and especially eastern or southern white immigrants.