plagal definition by Webster's New World
- designating a mode having a range about a fifth above and a fifth below a control note
- designating a cadence with the subdominant chord immediately preceding the tonic chord, as in the amen of a religious hymn
Origin: Midieval Latin plagalis ; from plaga, plagal mode ; from Medieval Greek plagios, plagal (in Classical Greek oblique, slanting) ; from Classical Greek plagos, a side, akin to pelagos, the sea: see pelagic
plagal definition by American Heritage Dictionary
Origin: Medieval Latin plagālis, from plaga, plagal mode, from plagius, plagal, from Medieval Greek plagios (ēkhos), plagal (mode), from Greek, oblique, from plagos, side; see plāk-1 in Indo-European roots.