The Collaborative International Dictionary of English v.0.48:

Timeless \Time"less\ (t[imac]m"l[e^]s), a.
   1. Done at an improper time; unseasonable; untimely. [R.]
      [1913 Webster]

            Nor fits it to prolong the heavenly feast
            Timeless, indecent.                   --Pope.
      [1913 Webster]

   2. Done or occurring before the proper time; premature;
      immature; as, a timeless grave. [Obs.]
      [1913 Webster]

            Must I behold thy timeless, cruel death? --Shak.
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   3. Having no end; interminable; unending. "Timeless night and
      chaos." --Young.
      [1913 Webster]

WordNet (r) 3.0 (2006):

timeless
    adj 1: unaffected by time; "few characters are so dateless as
           Hamlet"; "Helen's timeless beauty" [syn: dateless,
           timeless]