Aeonian and Timeless

Aeonian adjective - Of or relating to a geological eon (longer than an era).

Timeless and aeonian are semantically related. in constant topic. In some cases you can use "Timeless" instead an adjective "Aeonian", when it comes to topics like continual.

Timeless adjective - Having an existence or validity that does not change or diminish.

Aeonian and timeless are semantically related. You can use "Aeonian" instead an adjective "Timeless".