diatonic

adj. pertaining to a major or minor musical scale (made up of eight tones)

Diatonic and chromatic are terms in music theory that are most often used to characterise scales, and are also applied to intervals, chords, notes, musical styles, and kinds of harmony. They are very often used as a pair, especially when applied to contrasting features of the common practice music of the period 1600–1900.
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Adjective
1. based on the standard major or minor scales consisting of 5 tones and 2 semitones without modulation by accidentals
(antonym) chromatic
(classification) music
2. based on or using the five tones and two semitones of the major or minor scales of Western music
(similar) tonal

(a.)
Pertaining to the scale of eight tones, the eighth of which is the octave of the first.
  

muz. diatonic