Wiktionary
n. unify the people or peoples within a state so that it remains politically stable and viable in the long run
Wikipedia
Nation-building is constructing or structuring a national identity using the power of the state. It is thus narrower than what Paul James calls "nation formation", the broad process through which nations come into being. Nation-building aims at the unification of the people within the state so that it remains politically stable and viable in the long run. According to Harris Mylonas, "Legitimate authority in modern national states is connected to popular rule, to majorities. Nation-building is the process through which these majorities are constructed."
Nation builders are those members of a state who take the initiative to develop the national community through government programs, including military conscription and national content mass schooling. Nation-building can involve the use of propaganda or major infrastructure development to foster social harmony and economic growth.
Usage examples of "nation-building".
Beneath the conventionalities of his class the girl felt the man a powerful character, with all the latent strength of his nation-building ancestors.