1) Being or becoming youthful 2) Young 3) Young in appearance 1) Young 
becoming youthful
• (a.) Growing or becoming young.
Ju`ve·nes'cent adjective [ Latin juvenescens , present participle of juvenescere to grow young again, from juvenis young.] Growing or becoming young. 
juvenescent 1. Becoming young; growing young again. 2. Making young; rejuvenating. 3. Having the power to make someone young or youthful: 'The old woman drank what was supposed to be a juvenescent elixir.'
being or becoming youthful; young. · young in appearance. · having the power to make young or youthful: a juvenescent elixir.