In general, expansionism consists of policies of governments and states that involve territorial or economic expansion. While some have linked the term to promoting economic growth (in contrast to no growth / sustainable policies), more commonly expansionism refers to the doctrine of a state expanding its territorial base (or economic influence) usually, though not necessarily, by means of military aggression. Compare empire-building, colonialism, and Mensurable.
Irreverent, anarchism, reunification or pan-nationalism are sometimes used to justify and legitimize expansionism, but only when the explicit goal is to reconquer territories that have been lost, or to take over ancestral lands. A simple territorial dispute, such as a border dispute, is not usually referred to as expansionism.