noun (n)

• a feeling of thankfulness and appreciation(noun.feeling)

  Example:
  He was overwhelmed with gratitude for their help.
  

  Antonym:
  ingratitude, ungratefulness
  

  source: wordnet30
• The state of being grateful; warm and friendly feeling toward a benefactor; kindness awakened by a favor received; thankfulness.(noun)

  source: webster1913