LisbonPronunciation: /ˈlɪzbən/Translate Lisbon | into French | into German | into Spanish Definition of Lisbon the capital and chief port of Portugal, on the Atlantic coast at the mouth of the River Tagus; population 499,700 (2007). Portuguese name Lisboa /liʒˈbəʊə/. Lisbon in other Oxford dictionaries Definition of Lisbon in the US English dictionary