Arrested development is a term used to describe someone who has not progressed or matured emotionally, mentally, or socially. It is a condition that can be caused by various factors, such as environmental factors, genetic factors, or traumatic events. Synonyms for arrested development include immaturity, emotional stunting, mental stagnation, delayed development, social retardation, and infantilism. Other related words include being stuck, frozen in time, or trapped in a particular stage of development. It is important to seek professional help if you or someone you know experiences arrested development to address underlying issues and foster healthy growth and development.