Rio de Janeiro (re'o du zhäna'ro, Port. re'oo &thstrok;i zhunee'roo) city (1990 pop. 5,533,011; 1995 metropolitan area est. pop. 10,181,000), capital of Rio de Janeiro state, SE Brazil, on Guanabara Bay of the Atlantic Ocean. The second largest city and former capital of Brazil, it is the cultural center of the country and a financial, commercial, communications, and transportation hub. It has an international airport and a subway