American, when used as an adjective, can mean "of the United States of America" or "of or relating to the Americas"; when used as a noun, "United States citizen", "residing in the Americas", or less frequently "American English". Immigrants to the United States are usually called first-generation Americans, regardless of their citizenship status, and their children second-generation Americans.
As many people from the various nations throughout the New World consider themselves to be “Americans”, some think the common usage of American to refer to only people from the United States should be avoided in international contexts where it might cause confusion. Some find the use of American to refer to the United States only offensive, as tending to disregard the existence of other American nations. Some in Latin America may consider it an insult if it is suggested that they are somehow less worthy of being called American than residents of the USA. In Canada, however, American tends to refer to citizens of the United States only. Referring to a Canadian citizen as American is usually considered to be an insult. In some contexts, one would specify North American, Central American, or South American when the reference is to a continent or region. Other residents of the Americas do not feel such a broad sense of identity and think of themselves as citizens of their particular country, members of an ethnic group, or belonging to some other sub-continental entity. Many alternative neologisms to American have been proposed to refer to the United States, but they have failed to garner widespread acceptance. See Alternative words for American for more information.
While the use of American to refer to people and places elsewhere in the Americas was once fairly common in the United States, this use has declined in recent generations, to the point that many are uncomfortable with this usage.
English speakers most commonly use American to refer to the United States only; the same is true of cognates of the word in many other languages, such as the German Amerikaner, the French Américain(e), the Greek Αμερικανός (Amerikanos) and so on.
In Spanish, American tends to refer to any resident of the Americas and not necessarily the United States; English spoken in Latin America often makes this distinction as well. In Spanish, the normal term for U.S. citizens is estadounidense (literally United-Statesian). In the Iberoamerican countries, the use of americano (literally, "American") to describe a U.S. citizen could be considered culturally aggressive, because the word in Spanish habitually includes the inhabitants of the entire New World. In Portuguese, both in Portugal and Brazil, the term estadunidense is growing and it is considered more appropriate than the common term norte-americano (literally "North American"), as from a geographic view North America includes Mexico and Canada in addition to the United States.
The American race is an obsolete 19th-century racial classification referring to the various peoples now called Native Americans, also historically called the "red" race, although that latter term is generally considered derogatory.
The term American is also used to identify a type of railroad steam locomotive. In the Whyte notation, an 'American' locomotive is a type 4-4-0.