The Collaborative International Dictionary of English v.0.48:

Clemency \Clem"en*cy\, n.; pl. Clemencies. [L. clementia, fr.
   clemens mild, calm.]
   1. Disposition to forgive and spare, as offenders; mildness
      of temper; gentleness; tenderness; mercy.
      [1913 Webster]

            Great clemency and tender zeal toward their
            subjects.                             --Stowe.
      [1913 Webster]

            They had applied for the royal clemency. --Macaulay.
      [1913 Webster]

   2. Mildness or softness of the elements; as, the clemency of
      the season.

   Syn: Mildness; tenderness; indulgence; lenity; mercy;
        gentleness; compassion; kindness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

clemency
    n 1: good weather with comfortable temperatures [syn:
         mildness, clemency]
    2: leniency and compassion shown toward offenders by a person or
       agency charged with administering justice; "he threw himself
       on the mercy of the court" [syn: clemency, mercifulness,
       mercy]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "clemency":
   acceptance, benevolence, caritas, charity, clementness,
   commiseration, compassion, condolence, easiness, easygoingness,
   endurance, equitableness, fairness, favor, feeling, forbearance,
   forbearing, forgiveness, gentleness, grace, humaneness, humanity,
   indulgence, just, kindness, laxness, lenience, leniency,
   lenientness, lenity, mercifulness, mercy, mildness, mitigation,
   moderateness, pardon, pathos, patience, pity, quarter, relief,
   reprieve, ruth, self-pity, softness, sufferance, sympathy,
   tenderness, tolerance, toleration



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

CLEMENCY. The disposition to treat with leniency. See Mercy; Pardon.