The Collaborative International Dictionary of English v.0.48:

Kindness \Kind"ness\, n. [From Kind. a.]
   1. The state or quality of being kind, in any of its various
      senses; manifestation of kind feeling or disposition
      beneficence.
      [1913 Webster]

            I do fear thy nature;
            It is too full o' the milk of human kindness
            To catch the nearest way.             --Shak.
      [1913 Webster]

            Unremembered acts
            Of kindness and of love.              --Wordsworth.
      [1913 Webster]

   2. A kind act; an act of good will; as, to do a great
      kindness.

   Syn: Good will; benignity; grace; tenderness; compassion;
        humanity; clemency; mildness; gentleness; goodness;
        generosity; beneficence; favor.
        [1913 Webster]

WordNet (r) 3.0 (2006):

kindness
    n 1: the quality of being warmhearted and considerate and humane
         and sympathetic [ant: unkindness]
    2: tendency to be kind and forgiving [syn: forgivingness,
       kindness]
    3: a kind act [syn: kindness, benignity]

The Devil's Dictionary (1881-1906):

KINDNESS, n.  A brief preface to ten volumes of exaction.