relating to simple musical scales: relating to or based on musical scales consisting of five tones and two semitones, e.g. a major or minor scale with no extra sharps or flats added
noun (pluraldi·a·ton·ics)
Definition:
interval in diatonic scale: the interval between any two notes of a diatonic scale
[Early 17th century. Via French or late Latin< Greek diatonikos "at intervals of a tone" < tonos "tone"]