The definition I live by when it comes to the word "racism" is simply assigning personality characteristics to someone based solely on their race. Like going up to a black guy who happens to have been raised on a horse ranch in the Dakotas and assuming he listens to Jay Z. The assumption made in that example is that because he is black, he likes rap music and his individual background is either overlooked or disregarded. Assuming a white person is rich or privileged in some way is another example. It works in reverse too... assuming an asian person is good at math or knows martial arts... assuming that attorneys with Jewish names are going to be better than ones who don't. It takes many forms.