adult baby syndrome
/ˌæd.ʌltˌbeɪ̯.biˈsɪn.drəʊm/noun
RareNot in standard dictionaries
1
A condition or desire in which one takes on the role of an infant or toddler, usually by wearing diapers, engaging in child-like activities and engaging with childish paraphernalia, whether sexual (autonepiophilia) or non-sexual; infantilism, often believed to be the result of childhood trauma, neglect or abuse.
#informal#offensive