Replying to myself again. Guess it's obvious that I don't apply "Measure twice, cut once" to slashdot posts.
My above definition is not meant to presuppose that racism never happens due to ignorance on the part of the racist. I suppose my definition is motivated by the thought that a person willing to examine and change their racist thought patterns is at worst participating in racism due to laziness of thought, and at best due to such tunnel vision or restricted experience as to have not had a chance to think about such things.
A more accurate and probably uselessly general definition of a racist is anyone who ever engages in what I described in my first post.