The story
From adult baby + syndrome. First attested as early as 21 March 1994, but popularised in academia by a 2003 research paper (see quotations).
Etymology from Wiktionary, CC BY-SA 4.0.
adult baby syndrome
a·dult ba·by syn·dromeToday it means: 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. Full definition →