Common abbreviations of the United States of America include the United States, the U.S., and the U.S.A. Colloquial names for the country include the common America as well as the States. The term Americas, for the lands of the western hemisphere, was coined in the early sixteenth century after Amerigo Vespucci, an Italian explorer and cartographer. The full name of the country was first used officially in the Declaration of Independence, which was the "unanimous Declaration of the thirteen united States of America" adopted by the "Representatives of the united States of America" on July 4, 1776. The current name was finalized on November 15, 1777, when the Second Continental Congress adopted the Articles of Confederation, the first of which states, "The Stile of this Confederacy shall be 'The United States of America.'" Columbia, a once popular name for the Americas and the U.S., was named after Christopher Columbus. It appears in the name District of Columbia. A female personification of Columbia appears on some official documents, including certain prints of U.S. currency.

The standard way to refer to a citizen of the United States is as an American. Though United States is the formal adjective, American and U.S. are the most common adjectives used to refer to the country ("American values," "U.S. forces"). American is rarely used in English to refer to people not connected to the U.S. The prevailing use of American as synonymous with U.S. citizen has aroused controversy, particularly in Latin America, where Spanish and Portuguese speakers refer to themselves as "americanos" and use "estadounidense" to describe a person from the United States.