"Realism" in the philosophical sense has to be relative to something - Plato's essences, "collective imagination", society, truth are among the subjects that evoke comments that this person is a realist (considers the "something" to be real), and that one isn't.
A philosophical realist w.r.t. fairies is one who believes Fairies are real, while the non-realist says talk of fairies is due to overactive agency detectors or some such thing. It will tend to seem like the opposite of everyday use of the word "realism" -- at least if the subject is one non-philosophers would ever talk about.
I mention this only because I found it a bit difficult to get, and I think I've now "got" it. Correct me if you think I'm wrong.