A name that does two jobs
In ordinary English, America most often means the United States. The same word also names the larger landmass of North, Central, and South America, frequently in the plural as the Americas. Those two jobs sit on top of each other rather than replacing each other. The country sense is a later narrowing; the continental sense is older, and both still compete in careful writing.
The word did not grow out of Old English. It entered the language as a learned place-name coined in New Latin and then copied into maps, dictionaries, and verse.
A 1507 coinage, not a sailor's nickname
The form English later borrowed is New Latin America. It is first recorded in 1507, in a scholarly workshop at Saint-Dié, in what is now northeastern France. The cartographer Martin Waldseemüller issued a large printed world map and a short companion book, Cosmographiae Introductio. On the map the new name is written across the land now called South America. The book, written with or by Matthias Ringmann, treats the lands across the Atlantic as a fourth part of the world, added to Europe, Asia, and Africa.
The scholars built America as a feminine counterpart to Americus, the Latinized given name of Amerigo Vespucci, a Florentine navigator. Vespucci's printed letters, widely read in Europe in the first years of the sixteenth century, argued that the shores reached by Columbus were not the outer rim of Asia but a separate continent. He used the Latin tag Novus Mundus, New World. The Saint-Dié circle credited him with that conclusion and put his forename on the land. A given name was easier to Latinize than the surname: Vespucci as Vesputius might have yielded Vesputia, a form that never took hold.
They also tried Amerigen, from Amerigo plus a Greek word for earth. America prevailed because it lined up with the feminine names Europa, Asia, and Africa.
Standard references treat that chain as the origin of the word America. Vespucci's birth year is given as 1451 in some accounts and 1454 in others; he died in 1512. The disagreement does not change the naming story.
An Italian forename with a Germanic core
Amerigo is Italian, but it is not a Latin name at root. It belongs to a Germanic personal-name family that also produced German Emmerich and English surnames such as Emery, Emmerich, and Amery. Etymologists usually point to a compound of the type Amalariks: a first element tied to work, vigor, or the Gothic Amali line, plus riks, ruler. Older notes sometimes gloss a Gothic Amalrich as work-ruler. The picture is not perfectly tidy. The stock around Emmerich may blend more than one compound, including a home-ruler type related to Henry. For the place-name, the useful fact is narrower. English borrowed a New Latin geography term built on an Italian given name that had already moved from Germanic into Romance.
Cognate country names follow the same Latin stem: Italian America, Spanish América, French Amérique, German Amerika, Welsh America, Russian Америка. Those are sibling borrowings, not proof of a native English inheritance.
How the label widened, then narrowed
Waldseemüller's 1507 map used America for South America only. In 1538 Gerardus Mercator applied the name to the northern land as well and marked North and South America as separate continents. Waldseemüller himself had already wavered. On later work he dropped the personal tribute: a 1513 atlas calls the region Terra Incognita, and his 1516 Carta Marina uses Terra Nova. By then other mapmakers, including Johannes Schöner around 1515 and Peter Apian in 1520, had copied the 1507 naming, and the word was already in print beyond Saint-Dié.
English has it by about 1520. John Rastell's interlude of that year says the newly found land is called america because Americus is supposed to have found it first. Thomas Elyot's 1538 dictionary still describes America as a country lately found and still ties the name to Vespucci. From the seventeenth century onward, British colonial usage pulled the word toward the English settlements in North America. After independence it stuck to the United States.
By 1816 the lexicographer John Pickering could report that, wherever English was spoken, American was commonly understood as a person from the United States unless unusual precision was required. The mismatch was obvious to critics. In 1846 Edgar Allan Poe argued that Appalachia would be a clearer name for the country, because South America would never surrender America. Earlier coinages such as Fredonia were mocked and faded. The older, wider sense did not vanish. It remains in the Americas, Latin America, Central America, and in the title of the Organization of American States.
Two other stories, both thin
Rival explanations appear in popular writing and do not rest on early evidence. One credits Richard Amerike, also spelled Ameryk, a Bristol merchant with some connection to John Cabot's voyages. His surname is an English form of Welsh ap Meurig, son of Meurig. The claim depends on a manuscript copy whose crucial sentence is almost certainly a nineteenth-century insertion, made after the original burned in 1860. Another idea, in circulation since the late nineteenth century, points to the Amerrisque mountains in Nicaragua and a Mayan gloss sometimes given as country of the wind. No fifteenth- or sixteenth-century European source shows mapmakers taking the continent's name from that range. The mountain name may even have been reshaped after America was already famous, or the likeness may be chance.
The accepted account has its own limit. Vespucci did not find empty land. Indigenous peoples already lived there. What the Saint-Dié printers honored was a European argument: that those lands formed a continent of their own. That is why a forename, not a family name, landed on the map, and why a Germanic compound of the work-ruler type now names two continents and, in casual English, one country.