The Collaborative International Dictionary of English v.0.48:

Dismissal \Dis*miss"al\, n.
   Dismission; discharge.
   [1913 Webster]

         Officeholders were commanded faithfully to enforce it,
         upon pain of immediate dismissal.        --Motley.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dismissal
    n 1: a judgment disposing of the matter without a trial [syn:
         judgment of dismissal, judgement of dismissal,
         dismissal]
    2: official notice that you have been fired from your job [syn:
       dismissal, dismission, pink slip]
    3: permission to go; the sending away of someone
    4: the termination of someone's employment (leaving them free to
       depart) [syn: dismissal, dismission, discharge,
       firing, liberation, release, sack, sacking]

Moby Thesaurus II by Grady Ward, 1.0:

158 Moby Thesaurus words for "dismissal":
   abjuration, abjurement, absolution, acquittal, acquittance,
   adjournment, bounce, breakup, brush-off, cancellation, cashiering,
   chucking, chucking out, clearance, clearing, cold shoulder,
   compurgation, conge, contempt, contradiction, cut, deactivation,
   declination, declining, deconsecration, defrocking, demobilization,
   denial, deposal, deposition, deprivation, despisal, despising,
   destigmatization, destigmatizing, detachment, dethronement,
   diaspora, disapproval, disbandment, disbarment, disbarring,
   discard, discharge, disclamation, discounting, discrownment,
   disculpation, disemployment, disenthronement, disintegration,
   disorganization, disownment, dispersal, dispersion, displacement,
   displacing, disregard, dissolution, drumming out, end, exception,
   exclusion, excommunication, exculpation, excuse, exoneration,
   expulsion, firing, forced resignation, forced separation,
   forgiveness, furloughing, ignoring, impeachment, kicking upstairs,
   layoff, liquidation, nonacceptance, nonapproval, nonconsideration,
   notice, ousting, overthrow, overthrowal, pardon, parole, parting,
   passing by, pensioning off, pink slip, purgation, purge, purging,
   putting away, putting out, quietus, quittance, rebuff, recantation,
   refusal, rejection, release, remission, removal, renouncement,
   repudiation, repulse, retirement, sack, sacking, scouting,
   separation, snub, split-up, spurning, superannuation, surplusing,
   suspension, the ax, the boot, the bounce, the gate, the sack,
   throwing out, ticket, turning out, unbinding, unbolting,
   unbridling, unbuckling, uncaging, unchaining, unchurching,
   unfettering, unfrocking, ungagging, unhanding, unharnessing,
   unhobbling, unlashing, unlatching, unleashing, unlocking,
   unloosing, unmanacling, unmuzzling, unpenning, unseating,
   unshackling, unstrapping, untethering, untrussing, untying,
   unyoking, verdict of acquittal, vindication, walking papers