The authors agree that the surname derives from the personal name Lazzaro, whose etymology goes back to the Hebrew El'āzar, formed from El ("God") and āzar ("to help"), with the meaning "he who is aided by God". F. Miranda specifies that the name reached Italian by way of the Latin Lazarus and the Greek Lázaros, and that its remotest origin lies in the Aramaic La'zār. A. Bongioanni notes that the name also corresponds to the Hebrew form Eliezer, and that Saint Lazarus, brother of Martha and Mary raised from the dead by Jesus Christ, was identified in popular tradition with the Lazarus of the parable of the rich man, becoming the patron of lepers.

E. Rossoni adds that the surname may also have originated from place names such as Lazzaro in the Reggio Calabria area, Borgo San Lazzaro in that of Salerno, and San Lazzaro in those of Parma, Vicenza and Urbino, among others. Rossoni adds a historical and social sense: the lazzari or lazzaroni were young men of the lower classes of Naples during the 17th to 19th centuries; the term lazzarone comes from the Spanish "lázaros" —in reference to the rags of the evangelical Lazarus— and in common Italian came to mean a lazy or unreliable person.

Among the variants of the surname, Miranda mentions Lazzeri, Lazzero, Lazzarelli, Lazzaretti, Lazzeretti and Lazzarini. Bongioanni adds Lazzari, Lazzaretti, Lazzarini and Lazzaroni as derived or diminutive forms. Rossoni describes the geographical distribution of the variants: Lazzari is very widespread in northern Italy, in the Marche, Umbria and the Salento area —that is, the southernmost zone of the region of Puglia, in southern Italy—; Lazzarini extends across the whole north; Lazzaro predominates in the centre-south, in Veneto, in the Genoa area and in that of Cuneo; Lazzarone is proper to Piedmont, in the Asti and Turin areas; Lazzaroni is concentrated in Lombardy, with a presence also in the Bologna area.