The Collaborative International Dictionary of English v.0.48:

Yore \Yore\ (y[=o]r), adv. [OE. [yogh]ore, yare, [yogh]are, AS.
   ge['a]ra;akin to ge['a]r a year, E. year. [root]204. See
   Year.]
   In time long past; in old time; long since. [Obs. or Poetic]
   [1913 Webster]

         As it hath been of olde times yore.      --Chaucer.
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         Which though he hath polluted oft and yore,
         Yet I to them for judgment just do fly.  --Spenser.
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   Of yore, of old time; long ago; as, in times or days of
      yore. "But Satan now is wiser than of yore." --Pope.
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            Where Abraham fed his flock of yore.  --Keble.
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WordNet (r) 3.0 (2006):

yore
    n 1: time long past

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "yore":
   auld lang syne, days beyond recall, days of old, days of yore,
   early times, eld, foretime, good old times, lang syne, long ago,
   old days, old story, old times, olden times, same old story,
   the olden time, times of old, times of yore, way back, yesterday,
   yesteryear, yoretime