HanoiPronunciation: /haˈnɔɪ/Definition of Hanoi the capital of Vietnam, situated on the Red River in the north of the country; population 2,632,100 (est. 2009). It was the capital of French Indo-China from 1887 to 1946 and of North Vietnam before the reunification of North and South Vietnam. Hanoi in other Oxford dictionaries Definition of Hanoi in the US English dictionary