You searched for: “infantilism”
infantilism (s) (noun) (usually no plural form)
A condition of mental or physical underdevelopment, in which a person fails to mature sexually and emotionally; childish or immature behavior.
This entry is located in the following units: fa-, fam-, fan-, fant-, fat-, -fess; fab-, fabul- (page 4) -ism, -ismus (page 30)