Maybe we're getting into the unproductive game of definitions, but perhaps stereotyping is still stereotyping when the categories are completely made up.
After all, stereotyping implies incorrect categories. Otherwise it would be called classification.
Getting deeper into semantics, I have always understood stereotypes to be an essentially correct general average. Then of course people are so different that the average for a group fits no person in the group more than perhaps 30% so it always ends up being wrong when applied without thought.
But the general stereotype is not “completely made up” so to speak, it’s an observed average.
Then of course some total crap is always thrown in the mix but still.
From the viewpoint of the victims of a stereotype, I doubt that the degree of factual foundation which the stereotype possesses makes much of a difference.
Or based on a misunderstanding, but still coming from a real observation. For example in the US, apparently there used to be a stereotype that polish people are stupid, which came from language differences - polish immigrants had a lot more trouble with English than everyone else, or even were less likely to know any English.
A stereotype is a generalized belief about a category of people, I don't think there has to be any seed of accuracy to the categorisation in order for it to considered a stereotype.
Someone who believes in horoscopes has a stereotype for people born in the first part of April. I have a stereotype for first children. Whether or not they capture anything real, they still count as stereotypes.
