noun (n)

• any of 24 major or minor diatonic scales that provide the tonal framework for a piece of music(noun.communication)

  Synonym:
  key
  Antonym:
  atonalism, atonality
  

  source: wordnet30
• The principle of key in music; the character which a composition has by virtue of the key in which it is written, or through the family relationship of all its tones and chords to the keynote, or tonic, of the whole.(noun)

  source: webster1913