'Diatonic' definitions:

Definition of 'diatonic'

(from WordNet)
adjective
Based on the standard major or minor scales consisting of 5 tones and 2 semitones without modulation by accidentals [ant: chromatic]
adjective
Based on or using the five tones and two semitones of the major or minor scales of western music

Definition of 'Diatonic'

From: GCIDE
  • Diatonic \Di`a*ton"ic\ (d[imac]`[.a]*t[o^]n"[i^]k), a. [L. diatonicus, diatonus, Gr. ?, ?, fr. ? to stretch out; dia` through + ? to stretch: cf. F. diatonique. See Tone.] (Mus.) Pertaining to the scale of eight tones, the eighth of which is the octave of the first. [1913 Webster]
  • Diatonic scale (Mus.), a scale consisting of eight sounds with seven intervals, of which two are semitones and five are whole tones; a modern major or minor scale, as distinguished from the chromatic scale. [1913 Webster]