Avogadro is an Italian surname, derived from avogaro, a Venetian term for a diocese official (equivalent to avvocato, advocatus, "advocate"). In 1389, bishop Nicolò Beruti, made the office of avogaro hereditary, and a number of noble families with the name Avogaro or Avogadro developed over the following centuries, in Brescia, Vercelli and Treviso.