E. Rossoni places this surname mainly in the area between Mantua and Modena, with a broad diffusion in the Reggio Emilia, Bologna, Ferrara, Verona and Rovigo areas. As an early historical record of its fixing as a surname, Rossoni cites a deed of donation to a church of 1368, in Treviso, made by a Federico de' Malavasi of Breda di Piave. According to this author, the surname would derive from the medieval name Malavaxius or Malavasius, documented in sources of the 13th century relating to Rimini. Its origin would be a nickname based on the Latin vasum or vasus ("vessel"), with the figurative sense of "bad vessel".

F. De Laurentiis proposes a different reading: the surname would have arisen as a nickname compounded from mala and the personal name Vaso, regarded as an abbreviation of Gervaso. It would thus designate people of that name who enjoyed a bad reputation for their conduct.