Nowadays it is easy to google any word and find out what it means, but since a similar question is asked, it seems to me that a person wants a more detailed explanation, we will try to give it. Let's turn to the banal Wikipedia and take the definition from there. Schizophrenia (from ancient Greek σχίζω - to split, split and φρήν - mind, reason), earlier lat. Dementia praecox ("dementia premature") is a polymorphic mental disorder or a group of mental disorders  associated with the disintegration of thinking processes and emotional reactions . Schizophrenic disorders in general are characterized by characteristic fundamental disorders of thinking and perception, as well as inadequate or diminished affect.
It becomes clear that of all the functions of higher nervous activity, the process of thinking is most damaged, in simple terms thinking can be described as the process of cognizing the surrounding reality and establishing the relationship between various objects and phenomena of the objective world. Schizophrenia is different, there are several main forms, depending on which psychopathological syndrome prevails in the patient. Simple, starts early, is characterized for the most part by autism (isolation, unsociability, loss of interest in everything around) and apato-abulic syndrome (inactivity, complete loss of motivation, flattening (i.e., their absence) of emotions). Hebephrenic - characterized by the presence of foolishness and childishness in the behavior. Catatonic, which is characterized mainly by disorders of the motor sphere, agitation, stupor, the alternation of these states, etc. Well, the most common one is paranoid, as the name implies, it is characterized by various types of paranoid syndrome, classically often falls under the Kandinsky-Clerambo syndrome, pseudohallucinations (this is important, true hallucinations are usually observed in other disorders, our psychiatrist described them at one time V.Kh.Kandinsky, at the same time, he himself tested them), their distinguishing feature is that they do not have objective signs, they are difficult to describe, for example, if the patient hears voices, then they do not have timbre, pitch, are monotonous, are heard "as if from afar", and the patient also cannot say the woman is talking to him or the man, mental automatism (the patient feels that someone else is doing his actions for him, someone else thinks for him, etc. .) and delusions of influence (it seems to the patient that his thoughts are read and can change them, someone with the help of some devices makes him swear or something like that). In general, in psychiatry, this is the most common disease, more precisely, we can say that this is the most common reason for hospitalization and mainly in a psychotic. hospitals you will see exactly patients with schizophrenia. The most common, of course, depression (according to the American Association, by 2030, depression will come out on top in terms of incidence rate, overtaking cardiovascular diseases, by 2020 it will take second place, and thishour is at 4-5).
Severe mental illness, characterized by impaired connectivity of mental processes and a decline in mental activity. :))))))))))))))))))))))))))))