The term "Ugly American" refers to a stereotype American travelers abroad acting pedantic and condescending, often loud and annoying. In other words, the term refers to personality rather than physical appearance.
The term was gained traction from a popular 1958 novel The Ugly American that was made into a film in 1963 with the same name. Though the book centers on criticisms of American foreign policy and diplomacy, the term "Ugly American" usually refers to American travelers or tourists who are acting arrogantly or obnoxiously.
A negative term, it is best advised to avoid usage.
