American

adjective
of or connected with N or S America, especially the US
• I'm American.
• American culture/tourists  
Word Origin:
from modern Latin Americanus, from America, which dates from the early 16th cent. and is believed to derive from the Latin form (Americus) of the name of Amerigo Vespucci, who sailed along the west coast of South America in 1501.  
Culture:
America
The United States of America is called by several different names, both by the people who live there and by people in other countries. These names include the USA, the United States, the US, the States and America. The official name, the United States of America, first appears in the Declaration of Independence of 1776, when the country was called ‚the thirteen united States of America’. America is widely used as a name for the US, though this seems unfair on all the other nations in the Americas (= the continents of North and South America). Songs like America and America the Beautiful are about the US. Americans also use informal names like the US of A and Stateside, especially when they are out of the country. Other names, e.g. ‚the land of the free’, ‚the land of liberty’, ‚God’s country’, ‚the melting pot ’ and ‚the greatest nation on earth’, show their pride in their country. People in Britain and America sometimes refer humorously to each other’s countries as ‚the other side of the pond’, i.e. the other side of the Atlantic Ocean.
North America refers to a continent and region, and includes Canada and Mexico as well as the US. Between the US and South America is the region of Central America. Sometimes the countries of Central and South America are together referred to as Latin America.
America and the Americas are said to have been named after Amerigo Vespucci, an Italian explorerwho sailed to South America in 1499, visiting the area that later became known as Brazil, and also the Bahamas. Vespucci believed that the land he had discovered was a new continent, not part of Asia as Columbus had thought. By 1538, the famous map-maker Gerhardus Mercator was using the name ‚America’, the Latin form of Vespucci’s name, for the New World (= North and South America, as opposed to Europe).
People from the US are called Americans, though British people may, rather rudely, call them ‚Yanks’. People from other countries in the Americas are called by national names derived from the name of their country, e.g. Canadians. The adjective used to describe things from the US is American. The US is always referred to in organizations such as the American Legion and in expressions like ‚the American dream ’. US is also used as an adjective, as in the US Olympic team. Official names of government organizations may use United States, e.g. the United States Military Academy. 
More About:
America
The continent of America is divided into North America and South America. The narrow region joining North and South America is Central America.
North America, which is a geographical term, consists of the United States of America, Canada and Mexico. Latin America, a cultural term, refers to the non-English speaking countries of Central and South America, where mainly Portuguese and Spanish are spoken. Mexico is part of Latin America.
The United States of America is usually shortened to the USA, the US, the States or simply America: ▪ the US President ◊ ▪ Have you ever been to the States? ◊ ▪ She emigrated to America in 1995. Many people from other parts of the continent dislike this use of America to mean just the US, but it is very common.

American is usually used to talk about somebody or something from the United States of America: ▪ Do you have an American passport? ◊ ▪ American football ◊ ▪ I’m not American, I’m Canadian. Latin American and South American are used to refer to other parts of the continent: ▪ Latin American dance music ◊ ▪ Quite a lot of South Americans study here.