Babyishness is often associated with immaturity and childishness. However, there are several synonyms for this word that can describe a similar behavior or attitude. These include infantile, puerile, juvenile, naive, and childish. The term "infantile" implies a lack of development or progress in maturity, while "puerile" suggests a behavior that is silly or childish. "Juvenile" can mean both young and immature, while "naive" implies a lack of experience or sophistication. "Childish" is the most direct synonym for babyishness, indicating a behavior that is appropriate for a child but not an adult. Ultimately, the word chosen to describe such behavior can depend on the context and tone of the situation.