1.NounThe belief that there are distinct human races with inherent differences which determine their abilities, and generally that some are superior and others inferior.
2.NounThe policies, practices, or systems (e.g. government or political) promoting this belief or promoting the dominance of one or more races over others.
"Martin Luther King spoke out against racism."
3.NounPrejudice or discrimination based upon race or ethnicity; an action of such discrimination.