Original sentence: Irredentism is any political or popular movement that seeks to claim or reclaim and occupy a land that the movement's members consider to be a "lost" (or "unredeemed") territory from their nation's past.This wide definition, along with the possible lack of clarity of the borders of a nation or a people, allows the term to be used in a variety of situations, some of which are better described by other terms, such as expansionism
Edited sentence: Irredentism is the political policy or principle of attempting to achieve congruence between the borders of a sovereign state with the territory occupied by the people of the nation associated with that state, usually through territorial claims.This wide definition, along with the lack of clarity of the borders of a nation or a people, allows the term to be used in a variety of situations, some of which are better described by other terms, such as expansionism