A diatonic interval which traverses 8 steps in a diatonic scale, and covers a pitch distance bounded by 9 nominals inclusively, and octave plus a 2nd. This refers to the generic usage of "9th" without a qualifying adjective, which often precedes the interval name in standard diatonic usage. Thus, the various different types of diatonic 9ths are (in order of size from smallest to largest):
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