The name he is commonly called, "Fibonacci" (Italian: [fiboˈnattʃi]), was made up in 1838 by the French historian Guillaume Libri and is short for "filius Bonacci" ("son of (the) Bonacci") and he is also known as Leonardo Bonacci, Leon Fibonacci was an Italian mathematician from the Republic of Pisa, considered to be "the most talented Western mathematician of the Middle Ages". The name he is commonly called, "Fibonacci",ardo of Pisa, Leonardo Pisano Bigollo, or Leonardo Fibonacci.