in DSM–IV–TR and DSM–5, a rare disorder, most commonly but not exclusively found in young children, characterized by a persistent failure to speak in certain social situations (e.g., at school) despite the ability to speak and to understand spoken language.

n. a discrete episode of uncontrolled, excessive electrical discharge of neurons in the brain. The resulting clinical symptoms vary based on the type and location of the seizure. See epilepsy.

n. a discrete episode of uncontrolled, excessive electrical discharge of neurons in the brain. The resulting clinical symptoms vary based on the type and location of the seizure. See epilepsy.

a personality disorder characterized by various oddities of thought, perception, speech, and behavior that are not severe enough to warrant a diagnosis of schizophrenia. 

in DSM–IV–TR and DSM–5, a disorder whose essential features are identical to those of schizophrenia except that the total duration is between 1 and 6 months (i.e., intermediate between brief psychotic disorder and schizophrenia) and social or occupational functioning need not be impaired.

n. a psychotic disorder characterized by disturbances in thinking (cognition), emotional responsiveness, and behavior, with an age of onset typically between the late teens and mid-30s. 

a personality disorder characterized by long-term emotional coldness, absence of tender feelings for others, lack of desire for and enjoyment of close relationships, and indifference to praise or criticism and to the feelings of others.

in DSM–IV–TR, an uninterrupted illness featuring at some time a major depressive episode, manic episode, or mixed episodeconcurrently with characteristic symptoms of schizophrenia (e.g., delusions, hallucinations, disorganized speech, catatonic behavior) and, in the same period, delusions or hallucinations for at least 2 weeks in the absence of prominent mood symptoms. 

1. obsessional thinking involving excessive, repetitive thoughts or themes that interfere with other forms of mental activity.

in DSM–IV–TR, a disorder of infancy and early childhood characterized by disturbed and developmentally inappropriate patterns of social relating that are not due to intellectual disability or pervasive developmental disorder.

in DSM–IV–TR, a sleep disorder characterized by difficulty in initiating or maintaining a restorative sleep to a degree in which the severity and persistence of the sleep disturbance causes clinically significant distress, impairment in a significant area of functioning, or both.

a mood disorder in women that begins in the week prior to the onset of menstruation and subsides within the first few days of menstruation.

in DSM–IV–TR, a disorder that may result when an individual lives through or witnesses an event in which he or she believes that there is a threat to life or physical integrity and safety and experiences fear, terror, or helplessness.

n. a rare eating disorder marked by a persistent craving for unnatural, nonnutritive substances, such as plaster, paint, hair, starch, or dirt.

n. a rare eating disorder marked by a persistent craving for unnatural, nonnutritive substances, such as plaster, paint, hair, starch, or dirt.