Dysgrammatism is a disorder in language development that manifests itself in the incorrect application of grammatical rules when forming sentences and conjugating words. This becomes clear when sentences are incomplete or parts of sentences are twisted. Incorrect articles, cases or plural forms are used. Such mistakes also occur in normal language development. However, dysgrammatism is characterized by the fact that the child is not able to overcome these mistakes independently.

There are various reasons why dysgrammatism can develop. For example, if the linguistic input that a child needs to learn grammar is incorrect or does not meet their needs, the learning process can be hindered. If the working memory, which encodes what is heard and compares it with previously stored information, has too little capacity, information is lost before it can be stored in the long-term memory. In addition, the perception of chronological sequences and rhythm, which are used to determine the order of parts of sentences, may be impaired.

Dysgrammatism is not a purely linguistic phenomenon, but a qualitative structural language developmental anomaly that also affects other linguistic levels and other areas of development. Children who speak dysgrammatically often also have concentration and attention difficulties, symptoms of hyperactivity, limited memory span and memory capacity, as well as a poorly developed eagerness to speak.