The authors agree that the surname derives from the Latin given name Candidus, meaning "white", "pure" or "candid". Its hagiographic referent is Saint Candidus, venerated from the 8th century in Innichen, a locality of the Alto Adige known in Italian as San Candido.

E. De Stefani notes that in the 1st to 3rd centuries the name Candidus was frequent in Noricum, an Alpine area of the Roman Empire, and that over time it became a surname. In Friuli, the usual form of the Latin Candidus is Chiandit, a variant that De Stefani locates in Ruda, while the surname also appears in the Pordenone area —Maniago, Cordenons, Zoppola and Vivaro— and in localities of the Carnia such as Tolmezzo.

A. Bongioanni documents additional dialectal forms: Cándeo in Venetian, and Cándid, Çhandid, Çhandi and Çhandín in Friulian. From these bases surnames would have arisen such as the Venetian Cándeo and the Friulian Chiandetti, Chiandolini, Chiandotti, Chiandussi and Chiandussio. Bongioanni also specifies that the surname Candiani does not derive from the place name Candia but from the name Candidiano, and recalls that a Candidiano was patriarch of Grado between the years 606 and 612.

E. Rossoni adds that in southern Italy, especially in clusters of the Lecce and Taranto areas, a Greek-Albanian origin linked to the ethnic name of the island of Candia, present-day Crete, is not ruled out. He also notes the possibility of derivation from the place name Candida, in the Avellino area. The surname presents multiple independent clusters of origin, arisen in different regions without direct relation to each other, with presence documented in Friuli, Puglia, Calabria, Sicily, Lazio and Campania.