The authors agree that this surname continues the Latin auspicious name Bonus homo ("good man, honest, of high qualities"), which could also have functioned as a nickname given to the founding ancestor of each family line for his moral or behavioural merits, and which over time became a surname.

E. De Felice documents the oldest forms of the name: Bonushomo in Arezzo and Siena (715), Bonusomus and Bonusomulus in Lucca (761 and 769), Bonomine in Genoa (1062) and Bonomus in Padua (1275). He notes that the surname is especially diffused in northern Italy, in particular in Lombardy, and that the forms Bonomo and Bonomolo also appear in Sicily.

F. Miranda provides additional documentary testimonies: he records the form Bonushomos in deeds of sale of Pavia (1144) and in the Diplomatic Code of medieval Lombardy (1166). Miranda describes a wider geographical distribution that also covers Lazio, Veneto, Piedmont, Sardinia, Basilicata, Abruzzo, Campania, Tuscany, Liguria and Emilia-Romagna, with an extended presence in Sicily.