Some writers use "racism", some use "tribalism", some use "colorism", some use "ageism", some use "ableism"... Here's the first result when I googled "what 'isms' are there?"
The bottom line is, I think, we love to define "us" versus "them", or "others". It's natural to do so, because that's how we think--defining what something is by what it is not. When we do it to people, it's a problem.
