It used to mean you believed you were superior for being white but they've changed that now to make anyone racist by just bringing up something negative.

I literally have a paper copy of a 2012 Webster's Collegiate dictionary here on my lap - this is what it states.

racism 1: a belief that race is the primary determinant of human traits and capacities and that racial differences produce an inherent superiority of a particular race

2: racial prejudice or discrimination

-- racist n or adj

How they word it now had additions made (to fit their narrative).

racism 1: a belief that race is a fundamental determinant of human traits and capacities and that racial differences produce an inherent superiority of a particular race

2a: the systemic oppression of a racial group to the social, economic, and political advantage of another

b: a political or social system founded on racism and designed to execute its principles

-- racist noun or adjective

https://www.merriam-webster.com/dictionary/racism

See this article: https://www.vox.com/identities/2020/6/10/21286656/merriam-webster-racism-definition?__c=1