The authors agree that the surname has a dialectal root and originates in a physical nickname. F. Miranda notes that Truglio, together with its variant Trugli, would derive from the southern dialectal word trugghio or trugghiu, meaning "robust, sturdy, chubby, swollen". V. Blunda, for his part, specifies the Sicilian form trùgghiu, describing it as "plump, fat and firm", and adds that the adjective alludes to a stocky and vigorous build typical of Sicilian familiar speech, so that the surname would have arisen as a nickname applied to a person of a compact and recognisable body in their community.

Miranda also points to other possible etymologies: a toponymic derivation from places such as Truglio di Capri or Santo Stefano del Truglio, in the Rome area, and also the aphaeresis of the Neapolitan dialectal 'ntruglio, a term that designated a kind of agreement or negotiation over the penalty to be imposed on a defendant. As for its geographical distribution, Miranda indicates that the surname is concentrated mainly in Sicily, especially in the Messina and Catania areas, with a smaller presence in Lombardy, Campania, Lazio, Calabria, Tuscany and Emilia-Romagna.