What does 'Survivor Car' Mean?

This is a "survivor"

1964 Fury, unrestored, 28K original miles, original tires, hoses, belts, plugs, wires etc....brakes and exhaust were replaced but that's it.

My dad bought this from the original lady owner, the original tires are getting pretty rough so radials will be put on another set of rims so the factory ones can be saved and car can still be driven to shows.