The authors differ as to the origin of this surname. E. Rossoni considers that it would derive from the Slavic name Ladis, a contracted form of Ladisio and Ladislao, meaning "harmonious and handsome lord". Geographically, Rossoni places it as typical of the Bari area, with a presence concentrated especially in the city of Bari; the variant Ladisi would be much rarer and likewise proper to that same area.

V. Blunda, by contrast, proposes a Sicilian dialect origin: the surname would come from the word ddìsa, the dialect name of the ampelodesmos or Sicilian esparto grass, a wild grass used for plaiting ropes, mats and rural implements. According to Blunda, the surname may have arisen from a microtoponym referring to a spot where that plant grew in abundance, or else from the trade of the craftsman who worked it.

The divergence between the two proposals suggests that the surname has independent origins in different regions of Italy: one cluster in the Bari area, based on a personal name of Slavic root, and another in Sicily, of a dialect character and linked to the natural environment or to craft work.