Why was "tantrum" trending last week?
1932 as a noun, 1938 as an adjective, from race (n.2); racism is first attested 1936 (from French racisme, 1935), originally in the context of Nazi theories. But they replaced earlier words, racialism (1871) and racialist (1917), both often used early 20c. in a British or South African context. In the U.S., race hatred, race prejudice had been used, and, especially in 19c. political contexts, negrophobia.
The belief that some races are inherently superior (physically, intellectually, or culturally) to others and therefore have a right to dominate them. In the United States, racism, particularly by whites against blacks, has created profound racial tension and conflict in virtually all aspects of American society. Until the breakthroughs achieved by the civil rights movement in the 1950s and 1960s, white domination over blacks was institutionalized and supported in all branches and levels of government, by denying blacks their civil rights and opportunities to participate in political, economic, and social communities.