An arm of the South China Sea, bounded by the coasts of southern China and northern Vietnam. Its chief port is Haiphong. An incident there in 1964 led to increased US military involvement in the area prior to the Vietnam War.
Definition of Tonkin, Gulf of in US English:
Tonkin, Gulf of
proper noun
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.