The authors differ notably in the etymology of this surname. G. P. Holmes proposes a derivation from the Greek meaning "pebble", without further development.

F. Miranda offers a wider analysis and presents several hypotheses. The first links them to the phallic songs and feasts (phall-agōgía, φαλλ-αγωγία) celebrated in honour of the phallus in the Greek cult of Dionysus, a symbol of fecundity and transmission of life. A second hypothesis makes them derive from the place names Fàlica or Fàleca/o, localities in the province of Messina, or from the ancient Fàllichae Vicus, near Etna and cited by the historian Fazello. A third possibility, gathered by Ciccia in I cognomi di Paternò, relates them to the Calabrian Hàlaku, Fàlaku or Hàliku, meaning "rocky and inaccessible precipice".

According to Miranda, Fallico is the less widespread variant of the pair Fallico/Fallica, and is documented mainly in Sicily: in the Catania area (Bronte, Gravina di Catania), in the Enna area (Troina, Catenanuova, Centuripe), in the Syracuse area (Priolo Gargallo, Melilli, Augusta), and to a lesser extent in the Palermo and Messina areas.