Tonkin, Gulf of Syllabification: (Ton·kin, Gulf of)Definition of Tonkin, Gulf of an arm of the South China Sea, bounded by the coasts of southern China and northern Vietnam. Its chief port is Haiphong. An incident in 1964 led to increased US military involvement in the area. Tonkin, Gulf of in other Oxford dictionaries Definition of Tonkin, Gulf of in the British & World English dictionary
