Definition of tonkin:
(n) :
(historical) A former kingdom in northern Vietnam.
(n) :
(historical) A former protectorate in northern Vietnam, a colony of France.
(n) :
(archaic) Synonym of Hanoi, the capital of Vietnam.
(n) :
A surname transferred from the given name.
(n) :
Ellipsis of the Gulf of Tonkin: a gulf in northern Vietnam.
(n) :
Ellipsis of Gulf of Tonkin incident, a 1964 event used to increase US involvement in the Vietnamese Civil War.