Colonialism is the attempt by one country to establish settlements and to impose its political, economic and cultural principles in another territory".
Etymologically the base word "colony" comes from the Latin colōnia—"a place for agriculture".
Collins English Dictionary defines colonialism as "the policy and practice of a power in extending control over weaker peoples or areas". Webster's Encyclopedic Dictionary defines colonialism as "the system or policy of a nation seeking to extend or retain its authority over other people or territories". The Merriam-Webster Dictionary offers four definitions, including "something characteristic of a colony" and "control by one power over a dependent area or people".
The Stanford Encyclopedia of Philosophy "uses the term 'colonialism' to describe the process of European settlement and political control over the rest of the world, including the Americas, Australia, and parts of Africa and Asia". It discusses the distinction between colonialism, imperialism and conquest and states that "[t]he difficulty of defining colonialism stems from the fact that the term is often used as a synonym for imperialism. Both colonialism and imperialism were forms of conquest that were expected to benefit Europe economically and strategically.", and continues "given the difficulty of consistently distinguishing between the two terms, this entry will use colonialism as a broad concept that refers to the project of European political domination from the sixteenth to the twentieth centuries that ended with the national liberation movements of the 1960s".
In his preface to Jürgen Osterhammel's Colonialism: A Theoretical Overview, Roger Tignor says "For Osterhammel, the essence of colonialism is the existence of colonies, which are by definition governed differently from other territories such as protectorates or informal spheres of influence." In the book, Osterhammel asks, "How can 'colonialism' be defined independently from 'colony?'" He settles on a three-sentence definition:
Colonialism is a relationship between an indigenous (or forcibly imported) majority and a minority of foreign invaders. The fundamental decisions affecting the lives of the colonised people are made and implemented by the colonial rulers in pursuit of interests that are often defined in a distant metropolis. Rejecting cultural compromises with the colonised population, the colonisers are convinced of their own superiority and their ordained mandate to rule.