A disorder characterized by severe mental retardation but remarkable linguistic abilities is known as specific language impairment (SLI). This condition is also sometimes referred to as developmental language disorder or developmental dysphasia. Children with SLI have difficulty with language development, despite having normal hearing and intelligence. They may have difficulty with understanding and using language, including speaking, listening, reading, and writing. Children with SLI may also struggle with social communication skills, such as taking turns in conversation and understanding nonverbal cues. The cause of SLI is not fully understood, but it is thought to be related to genetics, brain development, and environmental factors.
The term "chatterbox" is sometimes used colloquially to describe someone who talks excessively.