inner child
noun [ C usually singular ] uk/ˌɪn.ə ˈtʃaɪld/ us/ˌɪn.ɚ ˈtʃaɪld/
童心
Your inner child is the part of your personality that still reacts and feels like a child.
Many therapists think it's important for adults to get in touch with their inner child. 许多治疗专家认为成年人保持童心很重要。