Leonardo of Pisa never called himself 'Fibonacci'. The first known mention of 'Leonardo Fibonacci' (Lionardo Fibonacci) is found in the records of the notary of the Holy Roman Empire, Perizolo (Perizolo da Pisa, Notaro Imperiale), from the year 1506. The word Fibonacci is a contraction of two words 'filius Bonacci', which appeared on the cover of the 'Book of Abacus'; they could mean either 'son of Bonaccio' or, if interpreting the word Bonacci as a surname, 'son of Bonacci'. According to a third version, the word Bonacci itself should also be understood as a nickname meaning 'fortunate'. He usually signed as Bonacci; sometimes he also used the name Leonardo Bigollo — the word bigollo in the Tuscan dialect meant 'wanderer', as well as 'idler'.
