octave, n.All

The Octave (n.) is ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠the 'same note' again only by our use of "same" — someone else might hear the same note after every four or three, calling tonic, dominant and octave the same.