A delusion, in everyday language, is a fixed belief that is either false, fanciful, or derived from deception.
I uncovered more an engrossing issue of delusions in a medical term. Everyone may have one of these delusions because everyone has a phobia (no matter how many). The phobia is actually developed by a negative/horror experience (physically or emotionally), a strong remembrance or presence of the previous dream in sleeping state. a negative/false influence and a previous indoctrination. When a person is in post-depression, he/she may suffer from or experience one or many of these. Sometimes a person can not accept deeply a painful truth which creates a big blow to him/her and becomes unstable mental. Related cases of a spouse in abusive marriage, a family member (mostly elderly and child) in domestic violence, an employee in corrupted management, a convict or a captive in abusive environment, a high loneliness of a person who live alone without social activities for a long period and etc.
Types of Delusion
Delusion of control which is a false belief that another person, group of people, or external force controls one’s thoughts, feelings, impulses or behavior.
Nihilistic delusion whose visualized centres on the nonexistence of self or parts of self, others, or the world. A person with this type of delusion may have the false belief that the world is ending.
Delusional jealousy (or delusion of infidelity): A person with this delusion falsely believes their spouse or lover is having an affair.
Delusion of guilt or sin (or delusion of self-accusation): This is a false feeling of remorse or guilt of delusional intensity.
Delusion of mind being read: The false belief that other people can know one’s thoughts.
Delusion of reference: The person falsely believes that insignificant remarks, events, or objects in one’s environment have personal meaning or significance.
Erotomania is a delusion in which one believes that another person is in love with him or her.
Grandiose delusion: An individual is convinced they have special powers, talents, or abilities.
Persecutory delusion: These are the most common type of delusions and involve the theme of being followed, harassed, cheated, poisoned or drugged, conspired against, spied on, attacked, or obstructed in the pursuit of goals.
Religious delusion: Any delusion with a religious or spiritual content. These may be combined with other delusions, such as grandiose delusions (the belief that the affected person was chosen by God, for example), delusions of control, or delusions of guilt.
Somatic delusion: A delusion whose content pertains to bodily functioning, bodily sensations, or physical appearance. Usually the false belief is that the body is somehow diseased, abnormal, or changed—for example, infested with parasites.
Smiliars to Diseases/Illnesses such as schizophrenia, paraphernalia, manic episodes of bipolar disorder, and psychotic depression.
See a list of rare ones.
In personal, someone under my roof is a most annoying person who does always stick what she is believing increasingly non-existant of something. It is more than a just normal person. Too much for me. As a observer, i can understand what that person goes through painful sufferings which may deteriorate her mental ability of judgement, comprehension and intellect.