The Collaborative International Dictionary of English v.0.48:

Remission \Re*mis"sion\ (r?-m?sh"?n), n. [F. r['e]mission, L.
   remissio. See Remit.]
   1. The act of remitting, surrendering, resigning, or giving
      up.
      [1913 Webster]

   2. Discharge from that which is due; relinquishment of a
      claim, right, or obligation; pardon of transgression;
      release from forfeiture, penalty, debt, etc.
      [1913 Webster]

            This is my blood of the new testament, which is shed
            for many for the remission of sins.   --Matt. xxvi.
                                                  28.
      [1913 Webster]

            That ples, therefore, . . .
            Will gain thee no remission.          --Milton.
      [1913 Webster]

   3. Diminution of intensity; abatement; relaxation.
      [1913 Webster]

   4. (Med.) A temporary and incomplete subsidence of the force
      or violence of a disease or of pain, as destinguished from
      intermission, in which the disease completely leaves the
      patient for a time; abatement.
      [1913 Webster]

   5. The act of sending back. [R.] --Stackhouse.
      [1913 Webster]

   6. Act of sending in payment, as money; remittance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

remission
    n 1: an abatement in intensity or degree (as in the
         manifestations of a disease); "his cancer is in remission"
         [syn: remission, remittal, subsidence]
    2: a payment of money sent to a person in another place [syn:
       remittance, remittal, remission, remitment]
    3: (law) the act of remitting (especially the referral of a law
       case to another court) [syn: remission, remitment,
       remit]
    4: the act of absolving or remitting; formal redemption as
       pronounced by a priest in the sacrament of penance [syn:
       absolution, remission, remittal, remission of sin]

Moby Thesaurus II by Grady Ward, 1.0:

140 Moby Thesaurus words for "remission":
   abatement, abeyance, absolution, acquittal, acquittance, allayment,
   alleviation, amnesty, assuagement, attrition, blunting, break,
   caesura, calming, catabasis, cease-fire, clearance, clearing,
   collapse, compurgation, crash, curtailment, cut, cutting, damping,
   day off, deadening, deceleration, declension, decline,
   decline and fall, decrease, decrement, decrescendo, deliverance,
   demulsion, depletion, depreciation, derogation, destigmatization,
   destigmatizing, detraction, diminuendo, diminution, dip, discharge,
   disculpation, dismissal, disparagement, dive, downtrend, downturn,
   drop, dulcification, dulling, dwindling, easing, ebb, ebbing,
   exculpation, excuse, exemption, exoneration, extraction, fall,
   falling-off, forgiveness, grace, hesitation, holiday, hushing,
   immunity, impairment, indemnity, indulgence, interim, interlude,
   intermezzo, intermission, intermittence, interruption, interval,
   lapse, layoff, leniency, lessening, letdown, letup, lightening,
   loosening, lull, lulling, mitigation, modulation, mollification,
   pacification, palliation, pardon, pause, plunge, purgation,
   purging, quietening, quieting, quietus, quittance, recess,
   redemption, reduction, relaxation, release, remission of sin,
   reprieve, respite, rest, retraction, retreat, retrenchment,
   shortening, shrift, shrinkage, slackening, slowdown, slump,
   softening, soothing, sparing, stand-down, stay, subduement,
   subsidence, suspension, tempering, tranquilization, truce,
   truncation, vacation, verdict of acquittal, vindication, wane



Bouvier's Law Dictionary, Revised 6th Ed (1856):

REMISSION, civil law. A release.
     2. The remission of the debt is either conventional, when it is
expressly granted to the debtor by a creditor having a capacity to alienate;
or tacit, when the creditor voluntarily surrenders to his debtor the
original title under private signature constituting the obligation. Civ.
Code of Lo. art. 2195.
     3. By remission is also understood a forgiveness or pardon of an
offence. It has the effect of putting back the offender into the same
situation he was before the commission of the offence. Remission is
generally granted in cases where the offence was involuntary, or committed
in self defence. Poth. Pr. Civ. sec t. 7, art. 2, Sec. 2.
     4. Remission is also used by common lawyers to express the act by which
a forfeiture or penalty is forgiven. 10 Wheat. 246.