Retreating to a dictionary definition doesn't argue against the point of the GP comment, namely: a white guy being called a cracker doesn't resonate with the kinds of cultural practices of oppression that that using racial slurs against a minority carries

If you're interested in arguing against that, do so. Posting definitions of words from dictionaries is the height of pedantic laziness in non sequitur form (unless the argument is actually about what the dictionary definition of a word is, of course).