[syn: ageless, aeonian, eonian, eternal, everlasting, perpetual, unending, unceasing]
The Collaborative International Dictionary of English v.0.48:
aeonian \aeonian\, AEonian \[AE]*o"ni*an\, a. [Gr. ?.]
   Eternal; everlasting; lasting for an indefinitely long time;
   immortal; not subject to death. Opposite of mortal.
   "[AE]onian hills." --Tennyson.
   Syn: eonian
        [1913 Webster + WordNet 1.5]
   2. of or pertaining to an eon.
      [WordNet 1.5]
WordNet (r) 3.0 (2006):
aeonian
    adj 1: of or relating to a geological eon (longer than an era)
           [syn: eonian, aeonian]
    2: continuing forever or indefinitely; "the ageless themes of
       love and revenge"; "eternal truths"; "life everlasting";
       "hell's perpetual fires"; "the unending bliss of heaven"
       [syn: ageless, aeonian, eonian, eternal,
       everlasting, perpetual, unending, unceasing]