noun
heptatonic scale; seven-note scale
Music theory term for any scale with seven notes per octave, such as the major or natural minor scale.
西洋音楽の長調や短調は七音音階に基づいている。
Western major and minor scales are based on the heptatonic scale.
Compound of 七 (しち, 'seven'), 音 (おん, 'note'), and 音階 (おんかい, 'musical scale').