noun.
The policy, of a nation, of expanding its territory or its economicinfluence
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
the doctrine of expanding the territory or the economic influence of a country
Word Usage
"One of the biggest problems in bringing Israel to its senses, and/or making it accountable for its egregious expansionism, is that the US populace has been cowed into equating anti-zionism with anti-semitism."