Ageless

adj. eternal, immortal; not showing signs of growing older

Ageless is an adjective describing something or someone whose age cannot be defined or is nonexistent.Agelessness can be attributed to people whose physical characteristics do not match their age. Some use cosmetics to attempt to diminish the effects of age. This use sometimes creates conflicting age indicators (for example, red hair belonging to a wrinkled face), making age determination difficult.
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Adjective
1. continuing forever or indefinitely; "the ageless themes of love and revenge"; "eternal truths"; "life everlasting"; "hell's perpetual fires"; "the unending bliss of heaven"
(synonym) eternal, everlasting, perpetual, unending, unceasing
(similar) permanent, lasting

(a.)
Without old age limits of duration; as, fountains of ageless youth.
  

Synonyms and related words:
age-old, ancient, antique, auld, ceaseless, coeternal, constant, continual, continuous, dateless, elderly, endless, eternal, eterne, ever-being, ever-durable, ever-during, everlasting, everliving, hoary, immemorial, incessant, indestructible, infinite, interminable, never-ceasing, never-ending, nonstop, nonterminating, nonterminous, of old, of yore, olamic, old, old as Methuselah, old as history, old as time, old-time, olden, perdurable, permanent, perpetual, sempiternal, steady, timeless, unceasing, unending, unintermitting, uninterrupted, unremitting, venerable, without end,