diminished seventh

noun

1

: a musical interval (see interval sense 2c)that is smaller than a seventh by a semitone

2

or diminished seventh chord : a seventh chord that is often built on the leading tone, that spans the interval (see interval sense 2c)of a diminished seventh (sense 1), and that consists of three minor thirds

called also diminished chord

see seventh chord

Word History

First Known Use

1753, in the meaning defined at sense 1

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