fu

Fu is a past form of essere, to be, used as an adjective meaning dead or deceased. Placed before a name, as figlio del fu Giovanni or della fu Rosa, it tells you that parent had died before the record was made. That single word can narrow the father's death to a window of years.

Compare di, of: Iorio Carmela di Vincenzo means Carmela Iorio, daughter of Vincenzo, and simply names her father, while fu would mark him as dead. Italian records also list the surname first, so read Rossi Mario as Mario Rossi. Fu also appears as an ordinary verb, as in fu battezzato, was baptized.