puerilism

plural puerilisms

1. uncountableusuallyhuman sciencesChildlike behavior by an adult, especially as indicating a mental disorder.

   [T]he Dutchman Johan Huizenga, who coined the term puerilism in the 1930s . . . defined it as permanent puberty.

   1962, Walter Laqueur, Young Germany: A History of the German Youth Movement, →ISBN, page xi

   2 more examples

   With regard to hysteria; in dissociation there may be a secondary time disorder; for example a patient with puerilism said: "People all seem grown up and older. And my Mum, I'm sure I know her from a long time ago. I look at her, but I can't make it out."

   1932, Aubrey Lewis, "The Experience of Time in Mental Disorder," reprinted in Inquiries in Psychiatry (Routledge, 2013), p. 14 (Google preview)

   A kind of puerilism marked many American attitudes — an unnaturally extended puerilism which tended to transmute itself into senility alarmingly and swiftly.

   2004, John Lukacs, A New Republic: A History of the United States in the Twentieth Century, →ISBN, page 286