dateless (Adjective) — Having no known beginning and presumably no end. ex. "the dateless rise and fall of the tides"
dateless (Adjective) — Of such great duration as to preclude the possibility of being assigned a date. ex. "dateless customs"
dateless (Adjective) — Not bearing a date. ex. "a dateless letter"
dateless (Adjective) — Unaffected by time. ex. "few characters are so dateless as Hamlet"