The Collaborative International Dictionary of English v.0.48:

Far \Far\, a. [Fartherand Farthestare used as the compar.
   and superl. of far, although they are corruptions arising
   from confusion with further and furthest. See Further.]
   [OE. fer, feor, AS. feor; akin to OS. fer, D. ver, OHG.
   ferro, adv., G. fern, a., Icel. fjarri, Dan. fjirn, Sw.
   fjerran, adv., Goth. fa[imac]rra, adv., Gr. ????? beyond,
   Skr. paras, adv., far, and prob. to L. per through, and E.
   prefix for-, as in forgive, and also to fare. Cf. Farther,
   Farthest.]
   1. Distant in any direction; not near; remote; mutually
      separated by a wide space or extent.
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            They said, . . . We be come from a far country.
                                                  --Josh. ix. 6.
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            The nations far and near contend in choice.
                                                  --Dryden.
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   2. Remote from purpose; contrary to design or wishes; as, far
      be it from me to justify cruelty.
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   3. Remote in affection or obedience; at a distance, morally
      or spiritually; t enmity with; alienated.
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            They that are far from thee ahsll perish. --Ps.
                                                  lxxiii. 27.
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   4. Widely different in nature or quality; opposite in
      character.
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            He was far from ill looking, though he thought
            himself still farther.                --F. Anstey.
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   5. The more distant of two; as, the far side (called also off
      side) of a horse, that is, the right side, or the one
      opposite to the rider when he mounts.
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   Note: The distinction between the adjectival and adverbial
         use of far is sometimes not easily discriminated.
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   By far, by much; by a great difference.

   Far between, with a long distance (of space or time)
      between; at long intervals. "The examinations are few and
      far between." --Farrar.
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WordNet (r) 3.0 (2006):

by far
    adv 1: by a considerable margin; "she was by far the smartest
           student"; "it was far and away the best meal he had ever
           eaten" [syn: by far, far and away, out and away]