imperialism

The extension of a nation’s authority by territorial acquisition or by the establishment of economic and political dominance over other nations.

A political doctrine or system promoting such extension of authority.

Imperial state or authority; the system of imperial government.

The principle or spirit of empire; promotion of or devotion to imperial interests.

Specifically

“In recent British politics, the principle or policy of seeking, or at least not refusing, an extension of the British Empire in directions where trading interests and investments require the protection of the flag; and of so uniting the different parts of the Empire having separate governments, as to secure that for certain purposes, such as warlike defence, internal commerce, copyright, and postal communication, they shall be practically a single state.”

In United States politics, the extension of the rule of the American government over foreign countries acquired by conquest or purchase, without a corresponding grant to them of the constitution or of a republican form of government; the governing of other peoples on the monarchical principle, as subjects rather than as citizens.

The power or character of an emperor; imperial authority; the spirit of empire.

The policy, practice, or advocacy of seeking, or acquiescing in, the extension of the control, dominion, or empire of a nation, as by the acquirement of new, esp. distant, territory or dependencies, or by the closer union of parts more or less independent of each other for operations of war, copyright, internal commerce, etc. The practise of building or extending an empire.

The policy of forcefully extending a nation‘s authority by territorial gain or by the establishment of economic and political dominance over other nations.