vietnamin is the singular genitive or singular genitive of Vietnam.

VietnamN

Norwegian Bokmål

VietnamN

Kven – Norwegian Bokmåldict-fkv-nob/src/Prop_fkvnob.xml:1739Edit on GitHub Suggest

Case	Sg
Nom	Vietnam / vietnam
Gen	Vietnamin / vietnamin
Par	Vietnamia / Vietnamii / vietnamia / vietnamii
Ill	Vietnamhiin / vietnamhiin
Ine	Vietnamissa / vietnamissa
Ela	Vietnamista / vietnamista