Any action, practice, or belief that reflects the racial worldview—the ideology that humans are divided into separate and exclusive biological entities called “races,” that there is a causal link between inherited physical traits and traits of personality, intellect, morality, and other cultural behavioral features, and that some “races” are innately superior to others.
Racism was at the heart of North American slavery and the overseas colonization and empire-building activities of some western Europeans, especially in the 18th century. The idea of race was invented to magnify the differences between people of European origin in the U.S. and those of African descent whose ancestors had been brought against their will to function as slaves in the American South. By viewing Africans and their descendants as lesser human beings, the proponents of slavery attempted to justify and maintain this system of exploitation
straight out the same dictionary you went to.