The Collaborative International Dictionary of English v.0.48:

Rectification \Rec`ti*fi*ca"tion\ (r?k`t?*f?*k?1sh?n), n. [Cf.
   F. rectification.]
   1. The act or operation of rectifying; as, the rectification
      of an error; the rectification of spirits.
      [1913 Webster]

            After the rectification of his views, he was
            incapable of compromise with profounder shapes of
            error.                                --De Quincey.
      [1913 Webster]

   2. (Geom.) The determination of a straight line whose length
      is equal a portion of a curve.
      [1913 Webster]

   Rectification of a globe (Astron.), its adjustment
      preparatory to the solution of a proposed problem.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rectification
    n 1: (chemistry) the process of refinement or purification of a
         substance by distillation
    2: the conversion of alternating current to direct current
    3: the act of offering an improvement to replace a mistake;
       setting right [syn: correction, rectification]
    4: determination of the length of a curve; finding a straight
       line equal in length to a given curve

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "rectification":
   amendment, amends, atonement, balancing, commutation, compensation,
   correction, counteraction, counterbalancing, editing, emendation,
   expiation, fixing, indemnification, indemnity, lex talionis,
   making right, mending, offsetting, overhaul, overhauling,
   recension, recompense, redaction, redress, remedy, repair,
   repairing, reparation, repayment, rescript, rescription,
   restitution, retaliation, revampment, revenge, revisal, revise,
   revised edition, revision, rewrite, rewriting, satisfaction,
   substitution, troubleshooting