The authors agree that this surname derives mainly from the Latin name Romanus, which originally designated the inhabitant of Rome. E. De Felice notes that in part it continues the Latin ethnic cognomen of the imperial period and in part it is a medieval Romance formation: in the Middle Ages, the term extensively designated all those belonging to the Roman Empire —both of the West and of the East—, including the Greeks, as opposed to peoples of a different ethnic tradition. E. De Stefani specifies that towards the 5th and 6th centuries, when Roman dominion had extended beyond the areas of the present-day Romania, Romanus came to indicate one who belonged to the Empire, as opposed to Alemanni, Lombards or Slavs.

F. Miranda broadens the etymological possibilities: the surname could also derive from the name of Slavic origin Roman, from place names such as Bassano Romano (province of Viterbo), Casalromano (province of Mantua), Romano Brianza (province of Como) or Romano Canavese (province of Turin), or else from the Arabic term rumman —"pomegranate"—, which designates the counterweight of the steelyard balance, so called for its shape similar to that fruit. P. Durante adds a complementary perspective: the surname may have a Greek origin, derived from Rhomaios, a term of the Eastern Roman Empire.

De Felice also notes that in some cases the base may be toponymic, from places called Romano frequent in northern Italy. R. Brondolo observes that the form Romanò, proper to the Lombardy area, is an apocope of Romanorum. De Stefani highlights that the form Romanutti is felt as typically Friulian, and documents the surname in the Carnia —a mountainous zone of northern Friuli, in the province of Udine— from the end of the 15th century.

As to the variants, De Stefani mentions Romanelli, Romanino, Romanin and Romanutti as forms derived by suffixation. De Felice notes that the forms Roman and those ending in -ati and -ato are proper to north-eastern Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige, while Romaniello is characteristic of the peninsular south, especially of the Naples area. Miranda adds that in Sicilian dialect rrumanu also designates the counterweight of the steelyard balance, which opens a possible professional interpretation of the surname in that region. N. Bergamo records numerous attestations in the Ligurian Ponente.