Source : Webster's Revised Unabridged Dictionary (1913)

Tonality \To*nal"i*ty\, n. [Cf. F. tonalit['e].] (Mus.)
   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.

         The predominance of the tonic as the link which
         connects all the tones of a piece, we may, with
         F['e]tis, term the principle of tonality. --Helmholtz.

Source : WordNet®

tonality
     n : any of 24 major or minor diatonic scales that provide the
         tonal framework for a piece of music [syn: {key}] [ant: {atonality}]