proper noun/tɔ̃.kɛ̃/
the northern part of Vietnam, a former French colonial region; a gulf in northern Vietnam: the Gulf of Tonkin
Related: golfe du Tonkin, haricot du Tonkin, Tonkinois, tonkinois
From Vietnamese Đông Kinh, a former name for Hanoi. Also see Pékin (“Beijing”) and Nankin (“Nanjing”).