The authors agree that the surname is of Germanic root and relate it to the compound Wil Hard. V. Blunda explains that this compound is formed by wil ("will, desire") and hard ("hard, valiant"), with the meaning "strong in will" or "firm in purpose", and notes that the root wil is the same one that gave rise to modern German Wille and English will.

F. Miranda adds a second hypothesis and considers it a probable modification of the surname Guagliardo or Gagliardo, itself derived from the medieval name Gagliardo, an Italianization of the Germanic personal name Gailhard, meaning "very vigorous". Miranda also notes a presence of the surname in Liguria, Emilia-Romagna, Umbria, Campania and Sicily, with localities documented in the Enna, Palermo and Agrigento areas.

Blunda, for his part, characterizes it as a phonetic variant of Ghilardi, with the consonant palatalization proper to southern Italian, and confines its origin specifically to Sicily.