(of a cadence) progressing from the subdominant to the tonic chord, as in the Amen of a hymn
2.
(of a mode) commencing upon the dominant of an authentic mode, but sharing the same final as the authentic mode. Plagal modes are designated by the prefix Hypo- before the name of their authentic counterparts
the Hypodorian mode
Compare authentic (sense 5)
Word origin
C16: from Medieval Latin plagālis, from plaga, perhaps from Greek plagos side
plagal in American English
(ˈpleɪgəl)
adjective Music
1.
designating a mode having a range about a fifth above and a fifth below a control note
2.
designating a cadence with the subdominant chord immediately preceding the tonic chord, as in the amen of a religious hymn
Word origin
ML plagalis < plaga, plagal mode < MGr plagios, plagal (in Gr, oblique, slanting) < Gr plagos, a side, akin to pelagos, the sea: see pelagic