gratitude
    n 1: a feeling of thankfulness and appreciation; "he was
         overwhelmed with gratitude for their help" [ant:
         ingratitude, ungratefulness]

Gratitude \Grat"i*tude\, n. [F. gratitude, LL. gratitudo, from
   gratus agreeable, grateful. See Grate, a.]
   The state of being grateful; warm and friendly feeling toward
   a benefactor; kindness awakened by a favor received;
   thankfulness.
   [1913 Webster]

         The debt immense of endless gratitude.   --Milton.
   [1913 Webster]