ageless

adjective
1
never looking old or never seeming to grow old
بی‌سن, همیشه‌جوان, جوان‌ماندگار
synonym timeless
2
existing forever; impossible to give an age to
جاودانه, ابدی, ازلی, بی‌زمان, همیشگی
the ageless mystery of the universe
synonym timeless