rac·ism
/ˈrāˌsizəm/
noun
prejudice, discrimination, or antagonism directed against a person or people on the basis of their membership in a particular racial or ethnic group, typically one that is a minority or marginalized. "a program to combat racism"
It's interesting how much salt these "no racism" posts generate from the overwhelmingly PPC userbase here.
We can read the definition - it describes prejudice, discrimination or antagonism. (I think the inclusion of the phrase “typically one that is a minority or marginalized” is unnecessary.) The issue is in the interpretation of the definition. For example, citing official crime statistics of certain ethnic groups clearly would not be racist. Yet many people would still consider it racist. That is the crap that needs to be avoided. Don’t play the racism card simply to shut people up.