Definition of plagal in English:

plagal

adjective

Music
  • (of a church mode) containing notes between the dominant and the note an octave higher.

    Compare with authentic
    • ‘The structure of authentic and plagal Modes was explained, and examples given of melodies formed on them.’

Origin

Late 16th century: from medieval Latin plagalis, from plaga plagal mode, from Latin plagius, from medieval Greek plagios (hēkhos) plagal (mode), from Greek plagos side.

Pronunciation:

plagal

/ˈpleɪɡ(ə)l/