The scholars consulted agree that this surname derives from the given name Lazzaro, of evangelical tradition: it is borne by the beggar in the parable of the rich man and by the brother of Mary and Martha raised from the dead by Christ. The name traces back, through the Latin Lazarus and the Greek Lázaros, to the Aramaic La'zàr, considered an abbreviated form of the Hebrew 'El'azar (that is, Eleazar). This compound of 'El — "God" — and 'azar — "to help" — carries the original meaning "God has helped," traditionally referring to a long-awaited and desired child.

E. De Felice observes that the surname is found with high frequency throughout Italy. He further notes that the variant Lazzeri is characteristic of Tuscany and the area of Florence, while the apocopated and derived forms — De Lazzari, Lazzarato, and Lazzarutti — are typical of the Veneto region. F. De Laurentiis concurs with the etymological derivation from the given name Lazzaro but does not add further geographic or formal detail beyond what De Felice provides. It is also recorded that the surname functions as a patronymic, meaning "son of Lazzaro."