The Collaborative International Dictionary
Hyphenated American \Hyphenated American\ An American who is referred to by a hyphenated term with the first word indicating an origin in a foreign country, and the second term being ``American'', as Irish-American, Italian-American, African-American, Asian-American. Used in reference to Americans of foreign birth or ancestry. When used of Americans of European ancestry, it is often used to refer to those who have a strong attachment to the ancestral country or its culture. It implies that the individual is imperfectly assimilated into American culture, and is sometimes used derogatively.
Wikipedia
In the United States, the term hyphenated American is an epithet commonly used from 1890 to 1920 to disparage Americans who were of foreign birth or origin, and who displayed an allegiance to a foreign country. It was most commonly used to disparage German Americans or Irish Americans ( Catholics) who called for U.S. neutrality in World War I. Former President Theodore Roosevelt was an outspoken anti-hyphenate and Woodrow Wilson followed suit.
The term "hyphenated American" was published by 1889, and was common as a derogatory term by 1904. During World War I the issue arose of the primary political loyalty of ethnic groups with close ties to Europe, especially German Americans and also Irish Americans. Former President Theodore Roosevelt in speaking to the largely Irish Catholic Knights of Columbus at Carnegie Hall on Columbus Day 1915, asserted that,
President Woodrow Wilson regarded "hyphenated Americans" with suspicion, saying, "Any man who carries a hyphen about with him carries a dagger that he is ready to plunge into the vitals of this Republic whenever he gets ready."
Usage examples of "hyphenated american".
I was born a hyphenated American in the East Bronx (Arthur Avenue and Fordham Road where Poe once walked with all his demons) coming in on a crash landing and still can't shake that hyphenated label - though now we live in a simpler place in time among the Litchfield Hills.