Amerigo Vespucci was a Florentine merchant and navigator who made at least two transatlantic trips to the New World, voyages that inspired cartographer Martin Wardseemüller to label the new continent "America" in 1507. Vespucci was employed by the Florentine Medici family as a representative for their operations in Seville, Spain. He went from supplying ships to joining the expedition of Alonso Ojeda as a navigator. Although the record is unclear, it is generally accepted that Vespucci sailed with Ojeda to the northeastern coast of South America in 1499, under the flag of Spain. He made a second voyage in 1502. The story that he reached South America in 1497 is held to be apocryphal; the story that he made a fourth voyage in 1504 is also considered suspect. Somehow an account of a 1497 voyage was published, and Wardseemüller came to believe that Vespucci had commanded the expedition and had reached the New World before Christopher Columbus, who found the mainland in 1498. Wardseemüller named the continent America and the label stuck.
Vespucci is said to have made a guess at the world's circumference that was accurate within 50 miles. His real achievement seems to be that he concluded America had to be a new continent and not the eastern part of Asia, as Columbus believed. An honored citizen in Spain, Vespucci spent the years after his voyages as a maritime official for King Ferdinand.
Amerigo Vespucci is sometimes latinized to Americus Vespucius.