Definition from Wiktionary, the free dictionary
Alternative forms 
- Contrary to the principles or institutions of United States.
- Not good for interest of United States.
- (US, spoken of another citizen) unpatriotic; non-xenophobic.
- Driving that fuel-efficient foreign car is downright unAmerican.
- (informal) incivil, immoral.
- For usage examples of this term, see the citations page.