from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An unidentified soldier killed in war and chosen to be interred with national honors as a representative of all those who died in a war.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- proper n. The WWI soldier whose body is buried in the Tomb of the Unknown Soldier.
- proper n. The representative of US military personnel who have died, usually in war, without proper burial.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an unidentified soldier whose body is honored as a memorial
Sorry, no etymologies found.
After all, if we could break up the Minsk Square - why it was named so is another story - and, along with it the Unknown Soldier as well, we could do anything to any heritage site.