Meaning

adjective based on the standard major or minor scales consisting of 5 tones and 2 semitones without modulation by accidentals

adjective based on or using the five tones and two semitones of the major or minor scales of western music

originFrom French diatonique or Late Latin diatonicus, ultimately from Ancient Greek διατονικός (diatonikós), in the phrase [γένος (génos, “type, genus”)] διατονικός (diatonikós) (in reference to the diatonic tetrachord, and in contrast to the chromatic and enharmonic tetrachords), from διάτονος (diátonos) (διά (diá) + τόνος (tónos)), of disputed etymology, as both components are ambiguous. Most…

Etymology from Wiktionary, CC BY-SA 3.0