OCCHIONERO, OCCHINERO, OCCHINEGRO: Consisting of two words: "occhio" = eye and "nero" = dark, black. To indicate the eyes color of a person
ODDI, ODDA, ODDONO, ODONE: From the first name Oddo, Otto, Odo of German origin
ODOARDI, ODOARDO: From the German first name Edoardo = guardian of the property
ODORISIO, ODORICO, ODERICO: From the first name Odorico of German origin meaning rich, noble
OLIVIERI: From the first name Oliviero
ORIENTE: From the word "oriente" = east, orient. To indicate, probably, the place of origin of the family
ORLANDI: From the first name Orlando, derived from the old name Rolando
ORSI, ORSINI, ORSELLI, ORSETTI, ORSOLINI: From the word "orso" = bear, used also as a nickname to indicate a strong person
ORTONA: From the name of the town of Ortona. To indicate someone coming from there
OTTAVIANO, OTTAIANO: From the first name Ottavio, derived from the noble family name "Octavia". Name given by the Romans to the 8th child born
OVIDIA, OVIDIO: From the first name Ovidio, derived from the Latin family name "Ovidius", from the word "ovis" = ship. Name given to a shepherd