The Collaborative International Dictionary of English v.0.48:

Replace \Re*place"\ (r?-pl?s"), v. t. [Pref. re- + place: cf. F.
   replacer.]
   1. To place again; to restore to a former place, position,
      condition, or the like.
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            The earl . . . was replaced in his government.
                                                  --Bacon.
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   2. To refund; to repay; to restore; as, to replace a sum of
      money borrowed.
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   3. To supply or substitute an equivalent for; as, to replace
      a lost document.
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            With Israel, religion replaced morality. --M.
                                                  Arnold.
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   4. To take the place of; to supply the want of; to fulfull
      the end or office of.
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            This duty of right intention does not replace or
            supersede the duty of consideration.  --Whewell.
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   5. To put in a new or different place.
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   Note: The propriety of the use of replace instead of
         displace, supersede, take the place of, as in the third
         and fourth definitions, is often disputed on account of
         etymological discrepancy; but the use has been
         sanctioned by the practice of careful writers.
         [1913 Webster]

   Replaced crystal (Crystallog.), a crystal having one or
      more planes in the place of its edges or angles.
      [1913 Webster]

WordNet (r) 3.0 (2006):

replace
    v 1: substitute a person or thing for (another that is broken or
         inefficient or lost or no longer working or yielding what
         is expected); "He replaced the old razor blade"; "We need
         to replace the secretary that left a month ago"; "the
         insurance will replace the lost income"; "This antique vase
         can never be replaced"
    2: take the place or move into the position of; "Smith replaced
       Miller as CEO after Miller left"; "the computer has
       supplanted the slide rule"; "Mary replaced Susan as the
       team's captain and the highest-ranked player in the school"
       [syn: supplant, replace, supersede, supervene upon,
       supercede]
    3: put something back where it belongs; "replace the book on the
       shelf after you have finished reading it"; "please put the
       clean dishes back in the cabinet when you have washed them"
       [syn: replace, put back]
    4: put in the place of another; switch seemingly equivalent
       items; "the con artist replaced the original with a fake
       Rembrandt"; "substitute regular milk with fat-free milk";
       "synonyms can be interchanged without a changing the
       context's meaning" [syn: substitute, replace,
       interchange, exchange]