english
1
general::
Having a youthful outlook, especially in spite of one's age. For example, She loves carnivals and fairs; she's a grandmother but she's young at heart.
American Heritage Idioms
2
general::
Phrase(s): *young at heart having a youthful spirit no matter what one’s age. (*Typically: act ~; be ~; keep someone ~; stay ~.) • I am over 70 but I still feel young at heart.
McGrawhill's American Idioms And Phrasal Verbs