Wiktionary
unyouthful
a. Not youthful.
Usage examples of "unyouthful".
Blank, rigid horror--tearless, voiceless, helpless despair, seemed to have petrified the expression of his face into an everlasting form, unyouthful and unhopeful--as if he had been imprisoned from his childhood, and a voice was now taunting him with the pleasures of liberty, from a grating in his dungeon walls.
A kind of tired, imploring expression masked his thin face, and there was an unyouthful sag about his shoulders.