un-American (adj.)youdaoicibaDictYouDict[un-American 词源字典]
"not characteristic of American principles or methods, foreign to U.S. customs," 1818, from un- (1) "not" + American (adj.).
Everything is un-American that tends either to government by a plutocracy or government by a mob. [Theodore Roosevelt, 1917]
[un-American etymology, un-American origin, 英语词源]