plagal mode

noun

Definition of plagal mode

: a church mode (such as Hypophrygian or Hypomixolydian) with the same final (see final entry 2 sense c) as its parallel authentic mode but with an ambitus a fourth lower A plagal mode is found a fourth below its authentic, and the final of the authentic serves also for the plagal.— Rupert Hughes, The Musical Guide, 1903 — compare authentic mode — see church mode illustration

First Known Use of plagal mode

1721, in the meaning defined above

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