The authors agree that the surname has a Germanic root, although they differ in their etymological analysis. E. Rossoni proposes that it could derive from the Provençal name Gaullart, although he considers more probable an origin in the medieval Germanic name Gaillardus, composed of gail ("joy") and hard ("hardness"), with the sense of "cheerful in hardness". He documents this name in a Remissio culpe et pene of 1313, which mentions a Gaillardus de La Barde.

V. Blunda proposes, on the other hand, a different etymology: the Germanic compound Walh Hard, formed by walh ("foreigner", especially of Celtic or Latin origin) and hard ("hard, valiant"), with the sense of "strong as a foreigner" or "valiant among the walhs". He notes that the root walh is the same that originated the ethnonyms Welsh and Walloon, as well as the place names Wales and Wallachia, and that in Germanic it designated the non-Germanic peoples of the south or west, in particular Celts and Romans.

As for the geographical distribution, Rossoni distinguishes several zones: a Tuscan presence of Galardi between the Pistoia, Siena and especially Florence areas, and another in the Salerno area. The variant Galardo appears in the Caserta and Salerno areas, in Campania, and also in the Crotone area. The variant Galeardi, extremely rare, is exclusive to the south of Italy. Blunda, for his part, places the surname in Sicily and notes its preservation in zones of the centre and south of Italy.