Definition of infantile

The word "infantile" originates from the Latin word "infantilis," which means "pertaining to an infant." This Latin term is derived from "infans," meaning "not speaking" or "unborn," and the suffix "-ile," which forms an adjective. In English, the word "infantile" was first used in the 15th century to describe something related to or characteristic of an infant, such as infantile behavior or infantile speech. Over time, the meaning of the word expanded to include connotations of immaturity, childishness, or a lack of maturity. Today, the word "infantile" is often used in psychology and psychiatry to describe behaviors or thought patterns that are characteristic of early childhood, but are also present in adults who may be experiencing developmental disorders or regressive behavior.