young at heart
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.
Queen of HeartsRead more in this article about some frequently asked questions and fun facts related to our definitions.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.