E. Rossoni notes that this is clearly a Sardinian surname, whose most likely origin goes back to a locality that once existed in the Ozieri area, in the province of Sassari, called precisely Ledda. An alternative hypothesis proposes that the name would derive from ledàmine, the Sardinian term for the month of October, of which ledda would be a contraction, thus alluding to the birth month of the founding ancestor. In the Sardinian language, this word also designates an ancient abandoned settlement and a mountain. The Vocabolario Sardo Geografico patronimico ed Etimologico of Giovanni Spano records that Ledda was a village destroyed in the diocese of Plaghe, whose ancient name was Lella, of possible Hebrew origin (Laila, "night"), on account of its northern location.

Rossoni further documents the presence of the surname in medieval Sardinian sources: it appears among the signatories of the Peace of Eleonora of 1388 in variants such as De Leda, De Ledda, Leda, Leddo, Ledu and Lella, and in the Condaghe of San Pietro di Silki (11th–13th centuries) the form De Lella also appears. For his part, F. De Laurentiis proposes a different etymology: the base would be the feminine personal name Leda or Ledda.