The authors agree that the surname may derive from an apocopated or hypocoristic form of the name Anastasio. E. De Felice describes it specifically as an aphaeretic hypocoristic —that is, with the loss of initial syllables— of the name Anastasio, and notes that it is documented mainly in southern Italy, with a presence also in the north-east of Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige.

E. Rossoni broadens the analysis with a second etymology: the surname could derive from the Latin cognomen Statius, illustrated by the celebrated writer of Neapolitan origin Publius Papinius Statius (45–96 AD). Rossoni further specifies that the form Anastasio comes from the Greek anástasis, meaning "resurrection". As for the geographical distribution, he places Stasi mainly in Apulia, Campania, Basilicata and Calabria; Stasio in the Naples and Salerno areas, with a presence also in Lazio; Stati in Capistrello, in the L'Aquila area; Stazi in Rome and Lazio, with groups between the Ancona and Perugia areas; Stazio in the Ancona and Naples areas; and Stazzi in Rome, where it is very rare.