Vietnam should be correctly written as Viet Nam . Viet is the name of the people, which covers the 54 different ethnic groups in the country. Nam means South. Viet Nam means the Viet people living in the South .
To many people, Vietnam is not an unfamiliar name as it had been on the international press and media for such a long time. But what have been left in their minds are just images of war in a secluded corner of Southeast Asia, nothing more. So hardly does anyone know the meaning of the name and the long established history of that remote country.
The name Vietnam came about when Emperor Gia Long desired to rename the country Nam Viet which was the combination of names of regions in Vietnam, including An Nam and Viet Thuong, and later change to Vietnam as seen today. There are many other assumptions about the meaning of the name and the most rational explanation is that the name is the fine combination of both geographical and ethnic factors.
In brief, Vietnam means the Viets of the South according to the second explanation or is synonymous with the reunification of different regions in Vietnam in accordance with the first explanation.