WordNet (r) 3.0 (2006):

timelessness
    n 1: a state of eternal existence believed in some religions to
         characterize the afterlife [syn: eternity,
         timelessness, timeless existence]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "timelessness":
   ceaselessness, coeternity, constancy, continualness, continuance,
   durability, endlessness, eternalness, eternity, ever-duringness,
   everlastingness, everness, foreverness, immutability, incessancy,
   indestructibility, infinite duration, infinity, interminability,
   never-endingness, perdurability, perenniality, perennialness,
   permanence, perpetualness, perpetuity, sempiternity, stability,
   unceasingness