Timeless; immortal
Without a date imprinted, assigned, or associated.
Out of one's head; deranged.
Thick-headed.
Having no date—a meeting with a lover or potential lover.
Without a start; immemorial
Eternal.
Not decreasing over time in quality and appeal.
Not affected by time; ageless.
A gene encoding an essential protein that regulates circadian rhythm, normally written in italics: timeless.