All grown up is a term that is commonly used to describe a person who has reached a level of maturity or adulthood. However, there are several synonyms for this phrase that individuals can use to express a similar sentiment. These may include phrases such as fully developed, matured, grown, or mature. Others may use terms such as independent, self-sufficient, or responsible to describe someone who has become an adult. Regardless of the synonym used, the term is typically used to indicate that an individual has reached a level of accomplishment, success, or personal growth in their life.