Delusion
A delusion is a false belief held by a person. When doctors talk about delusions, they mean that the false belief is the result of some disease. This is usually a disease of the mind, such as paranoia, schizophrenia or bipolar disorder, but not always. Delusions can come in many forms, such as persecutory delusions (a belief that the person is always being attacked), grandiose delusions (a belief that the person is very special), religious delusions (a belief that the person is a god), and more.