The film describes how Johnson was reviled for dating and marrying white women. There are frequent references to the term "miscegenation" and one reference to "octoroon." I kept thinking, "what kind of society is it that takes concepts like those so seriously that it actually assigns words to them?"
There are bazillions of other examples of questionable concepts reified by having words assigned to them, of course. And it can work the other way around too - important concepts can be promoted in society by having words assigned to them.