F. Miranda and V. Blunda agree that this is a surname of Sicilian dialectal origin, derived from the dialectal word trussu (also recorded as trùssu), which designates the core or central stalk of a cabbage, cauliflower or artichoke —that is, the hard part of the vegetable that is discarded when cooking. Both note that its use as a surname would have arisen from a nickname applied to the first bearer, possibly linked to physical characteristics or to a trade connected with the vegetable garden.

Miranda adds a second hypothesis, attributed to the scholar Caracausi, according to which Trusso could derive from the French trousse, with the sense of "bag" or as a reference to the trade of bag-maker. Miranda also notes that the surname is concentrated mainly in the Messina area —in localities such as Tortorici, Sant'Agata di Militello and Capo d'Orlando—, though it also appears in other provinces of Sicily such as Catania, Palermo, Syracuse and in the Enna area. Outside Sicily, there are zones of occasional presence in Lombardy, Piedmont, Tuscany, Calabria, Abruzzo and Liguria.

Miranda also documents a compound surname, Trusso Cafarello, typical of the Messina area, Tortorici and its surroundings, and present in the provinces of Messina, Catania and Enna. The second element, Cafarello, would derive —directly or through hypocoristic forms— from the medieval name Cafarus or Caffarus.