Having no known beginning and presumably no end:
— The dateless rise and fall of the tides.

synonyms: endless, sempiternal.

Of such great duration as to preclude the possibility of being assigned a date.

Not bearing a date:
— A dateless letter.

synonym: undated.

Unaffected by time:
— Few characters are so dateless as Hamlet.

synonym: timeless.

Polish: ponadczasowy, bezczasowy