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
Lasting past maturity without falling off.
Of data or a data structure: not transient or temporary, but remaining in existence after the termination of the program that creates it.
Describing a fractal process that has a positive Brown function
non-transient.
Obstinately refusing to give up or let go.
Insistently repetitive.
Indefinitely continuous.