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]