The authors agree that this surname derives from the Greek basilikós, "lordly, imperial", in turn related to basileús, "king". E. Rossoni notes that the etymon took in Medieval Latin the form Basilicus, with the sense of "regal", and that in the Basilicata area the term could specifically designate a "governor". Rossoni also adds a possible toponymic derivation from Basiglio, a locality in the Milan area whose archaic form was precisely Basilico.

V. Blunda analyses the surname from the Sicilian perspective and specifies that it originally functioned as a nickname applied to the ancestor for his lordly bearing. He notes its parallel with the surname Basile and records the variant Basiricò as a graphic adaptation of the same Greek etymon.

As for its distribution, Rossoni documents specific areas of presence: the surname Basilico appears in the Varese and Milan areas —with localities such as Saronno, Cogliate and Solaro— and has a cluster in Gissi, in the Chieti area; the variant Basilicò is very rare and seems to be circumscribed to the Trapani area; the form Basilio records small clusters in the Milan area and in the Potenza area.