General Brazilian
zonas metropolitanas
Most common usage in Brazilian Portuguese, especially in urban planning and government contexts
São Paulo
zonas metropolitanas / RMSP (Região Metropolitana de São Paulo)
Frequently referred to by specific regional acronyms
Rio de Janeiro
zonas metropolitanas / RMRJ (Região Metropolitana do Rio de Janeiro)
Used with regional designation
Portugal
zonas metropolitanas / áreas metropolitanas
Slightly less common; 'áreas metropolitanas' is preferred in European Portuguese