The authors agree that this surname derives from a dialect nickname based on the adjective gnech or nech (also gneccu or neccu in Ligurian), with a meaning that ranges between "sad", "bad" and "simple, naive". E. De Felice documents the form Nechus in Turin in 1363 and links the term to the Latin *nequus, with the sense "unjust, wicked". E. Rossoni, for his part, records the dialect gnècch with the meaning "listless, idle", proper to both Lombardy and Liguria.

As for geographical distribution, Rossoni specifies that the form Gnecchi is typical of Lombardy, with a presence concentrated in the Lecco, Bergamo and Brescia areas. De Felice agrees in pointing to Lombardy and also Piedmont as areas where this variant took root. The form Gnecco, by contrast, is proper to Liguria: Rossoni places it in Genoa and in Cicagna, a locality in the same area, while De Felice likewise mentions it in association with Liguria.