Plagal /(plā"gal)/

Pla·gal

Plagal

a.
  1. Having a scale running from the dominant to its octave; -- said of certain old church modes or tunes, as opposed to those called authentic, which ran from the tonic to its octave. (Mus.)

Phrases & Compounds
Plagal cadence
a cadence in which the final chord on the tonic is preceded by the chord on the subdominant.