The passive state is characterized by a contiguous 'passivating film' of solid corrosion products separating the metallic phase from the adjacent electrolyte. Corrosion in the passive state involves growth of the passivating film and/or transfer of metal ions through the film into the electrolyte.
Source:
PAC, 1989, 61, 19. 'Electrochemical corrosion nomenclature (Recommendations 1988)' on page 21 (https://doi.org/10.1351/pac198961010019)