The Meaning of "Anti-"

When I first encountered the term “anti-racism” I assumed, as I was meant to assume, that it referred to something used to oppose or combat racism -- much the way antibacterial soap is meant to kill bacteria or anti-itch cream is meant to cure itching. It has since become clear that the “anti” in anti-racism functions much more like anti-clockwise or antimatter. If the hands of the clock start spinning anti-clockwise, they still go round the clock. We use “antimatter” to refer to another kind of matter -- made of antiparticles, each of which has a counterpart in ordinary matter. In this sense, the prefix “anti-” means something like “as seen through a perverse mirror.”

It seems to me that prefix of “Anti-racism” -- like that of “anti-fascism” is meant in this sense.