Jean-Martin Charcot in the context of "Guillaume Duchenne de Boulogne"

Hysteria is a term used to mean ungovernable emotional excess and can refer to a temporary state of mind or emotion. In the nineteenth century, female hysteria was considered a diagnosable physical illness in women. It is assumed that the basis for diagnosis operated under the belief that women are predisposed to mental and behavioral conditions; an interpretation of sex-related differences in stress responses. In the twentieth century, it shifted to being considered a mental illness. Influential physicians the likes of Sigmund Freud and Jean-Martin Charcot had dedicated research to hysteria patients.

Currently, most physicians do not accept hysteria as a medical diagnosis. Today, psychiatrists may use the term to refer to behavior in which patients "imitate physical or psychological disorders of a kind that draws medical and nursing attention to them", usually as a self-deception rather than an attempt to defraud. The blanket diagnosis of hysteria has been fragmented into myriad medical categories such as epilepsy, histrionic personality disorder, conversion disorders, dissociative disorders, or other medical conditions. Furthermore, lifestyle choices, such as choosing not to wed, are no longer considered symptoms of psychological disorders such as hysteria.

In psychology, abnormality (also dysfunctional behavior, maladaptive behavior, or deviant behavior) is a behavioral characteristic assigned to those with conditions that are regarded as dysfunctional. Behavior is considered to be abnormal when it is atypical or out of the ordinary, consists of undesirable behavior, and results in impairment in the individual's functioning. As applied to humans, abnormality may also encompass deviance, which refers to behavior that is considered to transgress social norms. The definition of abnormal behavior in humans is an often debated issue in abnormal psychology.

Abnormal behavior should not be confused with unusual behavior. Behavior that is out of the ordinary is not necessarily indicative of a mental disorder. Abnormal behavior, on the other hand, while not a mental disorder in itself, is often an indicator of a possible mental or psychological disorder. A psychological disorder is defined as an "ongoing dysfunctional pattern of thought, emotion, and behavior that causes significant distress, and is considered deviant in that person's culture or society". Abnormal behavior, as it relates to psychological disorders, would be "ongoing" and a cause of "significant distress". A mental disorder describes a patient who has a medical condition whereby the medical practitioner makes a judgment that the patient is exhibiting abnormal behavior based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria. Thus, simply because a behavior is unusual it does not make it abnormal; it is only considered abnormal if it meets these criteria. The DSM-5 is used by both researchers and clinicians in diagnosing a potential mental disorder. The criteria needed to be met in the DSM-5 vary for each mental disorder.

Louise Augustine Gleizes (born 21 August 1861), known as Augustine or A, was a French woman who was publicly exhibited as a "hysteria" patient by neurologist Jean-Martin Charcot while she was held at the Salpêtrière Hospital in Paris.