The Collaborative International Dictionary of English v.0.48:

Benignity \Be*nig"ni*ty\, n. [OE. benignite, F. b['e]nignit['e],
   OF. b['e]nignet['e], fr. L. benignitas. See Benign.]
   1. The quality of being benign; goodness; kindness;
      graciousness. "Benignity of aspect." --Sir W. Scott.
      [1913 Webster]

   2. Mildness; gentleness.
      [1913 Webster]

            The benignity or inclemency of the season.
                                                  --Spectator.
      [1913 Webster]

   3. Salubrity; wholesome quality. --Wiseman.
      [1913 Webster]

WordNet (r) 3.0 (2006):

benignity
    n 1: the quality of being kind and gentle [syn: benignity,
         benignancy, graciousness] [ant: malignance,
         malignancy, malignity]
    2: a kind act [syn: kindness, benignity]

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "benignity":
   accommodatingness, act of grace, act of kindness, advantageousness,
   affability, affectionateness, agreeableness, amiability,
   auspiciousness, benefaction, beneficence, beneficialness, benefit,
   benevolence, benignancy, blessing, brightness, brotherhood,
   cheerfulness, cheeriness, class, cogency, compassion, complaisance,
   compliance, courtesy, decency, desert, excellence, expedience,
   fairness, favor, favorableness, feeling of kinship, fellow feeling,
   fineness, first-rateness, fortunateness, fraternal feeling,
   generousness, good auspices, good deed, good offices, good omen,
   good turn, goodliness, goodness, goodness of heart, grace,
   graciosity, graciousness, harmlessness, healthiness, heart of gold,
   helpfulness, humaneness, humanity, hurtlessness, innocence,
   innocuousness, inoffensiveness, kind deed, kind offices,
   kindheartedness, kindliness, kindly act, kindly disposition,
   kindness, labor of love, loving kindness, luckiness, mercy, merit,
   mitzvah, niceness, obligation, obligingness, office, pleasantness,
   profitableness, propitiousness, prosperousness, quality,
   rewardingness, service, skillfulness, softheartedness,
   soul of kindness, soundness, superiority, sympathy,
   tenderheartedness, turn, uninjuriousness, unobnoxiousness,
   usefulness, validity, value, virtue, virtuousness, warmheartedness,
   warmth, warmth of heart, wholeness, worth