Ma·cao (mə-kou′) See Macau. Macao (məˈkaʊ) n (Placename) a special administrative region of China, in the south of the country, across the estuary of the Zhu Jiang from Hong Kong: chief centre of European trade with China in the 18th century; attained partial autonomy in 1976; formerly (until 1999) a Portuguese overseas province under a long-term …