1. (music) based on the standard major or minor scales consisting of 5 tones and 2 semitones without modulation by accidentals
   "The piece was composed using a diatonic scale"
    
2. Based on or using the five tones and two semitones of the major or minor scales of western music
   "The diatonic melody used only the notes of the C major scale"

See also: tonal

Antonym: chromatic

Encyclopedia: Diatonic