Ameriphobia is a term used by bloggers to describe either one of two things.
- 1. An irrational fear or hatred of the United States of America.
- 2. Anybody remotely liberal/left-wing who dares to criticize America, meaning that they must hate the U.S.A.
 The first kind
An irrational fear of the United States actually is an issue among certain politicians and groups. Conspiracy theories are the most common form, such as exaggerating the power of the US or treating it as the source of all evil. The leader of the Communist Party of the Russian Federation Gennady Zyuganov is big on this, claiming, for example, that the deaths of Hugo Chavez and other Latin American leaders who were critical of American foreign policy were caused by the US giving them diseases. Venezuelan Vice President Nicolas Maduro similarly claimed that the death of Hugo Chavez was caused by Americans giving him cancer.
Islamic fundamentalists and terrorist organizations often portray America as a great Satan that wishes to destroy Islam itself and promote sinfulness in its place. Conspiracy theories such as Moon landing hoax and America being a tool of the New World Order or Illuminati may pop up as well.
 The second kind
The word is also used by American right-wingers and conservatives, as a slur against those who disagree with them. These groups portray virtually anybody who doesn't believe America is the greatest country in the world, or criticizes American policies, as being "Ameriphobic". Basically, "If you don't agree with us, you must hate America".
Of course, these people tend to also be Europhobic and many of the comments they make about Europe are extremely similar to what Islamic Fundamentalists say about America, mainly "they're Godless secularists!"
In a sense many wingnuts apply a "with us or against us" dichotomy that boils down to "you either believe in American exceptionalism or you are an Ameriphobe". Of course the fact that the real world is never black and white is lost to them. For instance, such wingnut don't seem to realize that it's possible to oppose certain US administrations and/or specific US policies without being anti-American, but then again, such wingnuts tend to hold similar views of their domestic opponents (though the sobriquet tends to be un-American, rather than anti-American).