The authors agree that the surname derives from the Germanic given name compounded from land ("land, territory") and bert / berht ("illustrious, bright, famous"), with the overall meaning of "illustrious through the land" or "famous in the territory".

V. Blunda notes that the root land gave modern German Land and appears in numerous personal names such as Landolfo, Landulfo, Landeberto or Orlando, all linked to the original Germanic sense of territorial property. Blunda also details the hagiographic figure: Saint Lambert of Maastricht (c. 636–705), bishop and martyr, was murdered in Liège for defending Christian morality against the abuses of the court of Pepin of Herstal, and became patron of the diocese of Liège, where his cult remains active.

A. Bongioanni stresses that the name was very widespread and generated a broad family of derived surnames: Lamberti, Lambertazzi, Lambertini, Lambertoni and Lambertenghi, among others. He also notes that it shares with Alberto, Roberto and other names the suffix -bert, which explains the parallel series Berti, Bertacchi, Bertazzi, Bertini, Bertoni, and so on. Bongioanni further records the variant Lampertico, documented in the Vicenza area and possibly originating in the Sette Comuni, where the phonetic change b → p is characteristic of local speech.