Rio de Janeiro /ˈɹiːoʊ dɪ ʒəˈnɪəɹoʊ/ noun2 •A state of the Southeast Region, Brazil. Capital: Rio de Janeiro. •A municipality, the state capital of Rio de Janeiro, Brazil; the former capital of Brazil.In Rio de Janeiro, thousands protested in a gritty area far from the city’s upscale seaside districts. — 2013