Wikipedia says: Racism is actions, practices or beliefs, or social or political systems that consider different races to be ranked as inherently superior or inferior to each other, based on presumed shared inheritable traits, abilities, or qualities. [emphasis mine]
This definition is inadequate for two reasons:
1) It quells rational observation and discussion about race
Any time I want to make an observation based on racial/cultural characteristics, I am being racist.
If I comment that Ethiopians, on average, make superior long distance runners because of their body type, I am being racist.
If I observe that African American family formation in the United States is inherently inferior due to a high rate of out of wedlock childbirth, I am being racist.
If I brace myself for inferior driving when I go to Cupertino's Ranch 99 Plaza, I'm stereotyping Asians as poor drivers and am therefore being racist.
2) It's not helpful because it necessarily means we are all racist
Therefore anyone who makes a generalization about people of a certain race - and if it even remotely leans towards superiority/inferiority in some area - then I am a racist. If that's the definition, then everyone is a racist and if we claim otherwise, we are lying to ourselves.
Racial minorities are the worst. We make superiority/inferiority claims all the time about our own race but get angry when other races make comments about us. As if racism regarding our own race is acceptable but for other races to comment on us, it's wrong. That's a double standard if I ever saw one.
Racism is denial of equal value
This is why Amy Chua's books are so controversial because she is making observations about race and culture that she links to superior outcomes. Her stuff is based on research and her conclusions are logical but because she writes about racial superiority in certain aspects, BOOM - she's a racist.
I would add two words to the Wikipedia definition. I would redefine racism as the belief that races are inherently superior or inferior IN VALUE. Racism denies equality in value between races. We confuse all the other stuff - athletic prowess, intelligence, etc. as indicators of value. But they are not the same thing.
The idea that races are different and superior in certain regards is biblical. The Jews are the chosen people of God. Salvation comes from the Jews (Romans 1:16, John 4:22). God therefore must be racist for allowing Israel to have superior access to God.
And yet God affirms that all races are equal in value before God. Each person, regardless of race, has equal dignity and worth because of Christ (Galatians 3:28, Colossians 3:11). That is an important distinction and nowhere near saying all races are all equally good (or bad) at everything.