The Collaborative International Dictionary of English v.0.48:

Recession \Re*ces"sion\ (r[-e]*s[e^]sh"[u^]n), n. [L. recessio,
   fr. recedere, recessum. See Recede.]
   1. The act of receding or withdrawing, as from a place, a
      claim, or a demand. --South.
      [1913 Webster]

            Mercy may rejoice upon the recessions of justice.
                                                  --Jer. Taylor.
      [1913 Webster]

   2. (Economics) A period during which economic activity, as
      measured by gross domestic product, declines for at least
      two quarters in a row in a specific country. If the
      decline is severe and long, such as greater than ten
      percent, it may be termed a depression.
      [PJC]

   3. A procession in which people leave a ceremony, such as at
      a religious service.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Recession \Re*ces"sion\, n. [Pref. re- + cession.]
   The act of ceding back; restoration; repeated cession; as,
   the recession of conquered territory to its former sovereign.
   [1913 Webster]

WordNet (r) 3.0 (2006):

recession
    n 1: the state of the economy declines; a widespread decline in
         the GDP and employment and trade lasting from six months to
         a year
    2: a small concavity [syn: recess, recession, niche,
       corner]
    3: the withdrawal of the clergy and choir from the chancel to
       the vestry at the end of a church service [syn: recession,
       recessional]
    4: the act of ceding back [syn: recession, ceding back]
    5: the act of becoming more distant [syn: receding,
       recession]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "recession":
   abandonment, alcove, backset, backsliding, backward motion,
   backward step, bad times, bay, boom, bottoming out, business cycle,
   business fluctuations, bust, capitulation, cession, cooling off,
   corner, cove, crisis, decline, depression, dip, downturn,
   economic cycle, economic expansion, economic growth,
   economic stagnation, evil day, expanding economy, expansion,
   giving in, giving over, giving up, growth, hard times,
   heavy weather, high growth rate, inglenook, lapse, low,
   market expansion, niche, nook, peak, peaking, pitchhole,
   prosperity, rainy day, reaction, recedence, recess, recidivation,
   recidivism, recovery, reentry, refluence, reflux, regress,
   regression, relapse, relinquishment, renunciation, retreat,
   retroaction, retrocession, retroflexion, retrogradation,
   retrogression, retrusion, return, rollback, sad times, setback,
   slowdown, slump, stagnation, sternway, stormy weather, surrender,
   throwback, upturn