The surname has independent clusters of origin according to the sources consulted, with differing etymologies and geographical distributions.

E. Rossoni proposes that Lattari would derive from Mount Lattaro, situated in the vicinity of Vesuvius, in the region of Campania. According to this author, the surname is typical of the region of Calabria, with a particular concentration in the Cosenza area, and it further shows a probably secondary pocket in Rome.

V. Blunda offers an independent explanation of Sicilian origin: the surname would come from the dialect word lattàru, meaning "milkman" or "seller of milk", and would have arisen as a reference to the trade of one who dealt in milk. Blunda further notes that the variant Latteri reflects the a/e vowel alternation proper to Sicilian.

The two proposals therefore point to different geographical and semantic origins: while Rossoni links it to a Campanian place name established in Calabria, Blunda connects it to an occupational term proper to the Sicilian dialect.