The set of surnames derived from the roots Chiari- / Chiaro- / Chiara- forms a wide family of surnames of great diffusion in Italy, with origins that lie mainly on the anthroponymic plane, although in some cases they may also present developments of a toponymic type.

In general terms, the authors agree that these forms refer to the medieval Latin name Clarus, coming from the adjective clarus, meaning "clear", "luminous", "resplendent" or "illustrious". This name gave rise both to the masculine form Chiaro and to the feminine Chiara or Clara, which became consolidated especially in the Late Middle Ages thanks to the expansion of the cult of Saint Clare of Assisi, a central figure in the diffusion of the feminine name in the European Christian sphere. In parallel, a direct derivation from the adjective chiaro is also possible, used as the base of descriptive nicknames linked to physical, moral or symbolic qualities.

According to E. De Felice, the variants with the base Chia- are widely distributed throughout Italy, with greater concentration in the northern regions (the Venices, Emilia and Tuscany) and significant presence also in the centre and south. The author also highlights the richness of regional forms: in Campania variants appear such as Chiariello, Chiarullo, Chiarolla or Chiarolanza; in Tuscany Chiarante and Chiarugi are recorded; in Puglia, Chiarantoni; while in Friuli-Venezia Giulia forms with the base Cla- predominate. The endings in -ato, -atto and -utti are typical of the Triveneto area, reflecting local dialectal adaptations.

For his part, E. Rossoni broadens the picture by noting that these surnames may also have a toponymic origin, linked to localities such as Chiari (Brescia) or Chiarone (Grosseto). He also details specific regional distributions: Chiari is concentrated in the Bergamo, Parma and Tuscan-Umbrian areas; Chiarini extends between Brescia and the strip that covers Bologna, Ferrara, Ravenna, Florence and Pistoia; Chiaro presents clusters in Naples, Venice and Reggio Calabria; while Chiarugi is characteristic of Tuscany.

As a whole, these interpretations show a multiple origin where the Latin name Clarus, the evolution of the medieval cult of Chiara, the use of the adjective as a nickname and the possible influence of place names converge, giving rise to a family of surnames widely spread and regionally diversified throughout the Italian peninsula.