plainsong

[ pleyn-sawng, -song ]

/ ˈpleɪnˌsɔŋ, -ˌsɒŋ /

the unisonous vocal music used in the Christian church from the earliest times.

modal liturgical music; Gregorian chant.

a cantus firmus or theme chosen for contrapuntal development.

any simple and unadorned melody or air.

Also called plainchant (for defs 1, 2).

Origin of plainsong

1505–15; translation of Medieval Latin cantus plānus

Music embraced the rules of the plain-song of the Church, some theory of sound, and the connexion of harmony and numbers.

Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10 |Various
Under Fulbert, indeed, the school of Chartres became famous for its music and for its plain-song renderings of the sacred offices.

The Story of Chartres |Cecil Headlam
It may be beautiful in secular music, but it is null and void when it attempts the venerable sequences of plain-song.

The Cathedral |Joris-Karl Huysmans
A plain-song by Alexander Reinagle is used by some congregations, but is not remarkably expressive.

The Story of the Hymns and Tunes |Theron Brown and Hezekiah Butterworth

When opposed to plain-song, it meant counter-point as distinguished from mere melody.

Shakespeare's Tragedy of Romeo and Juliet |William Shakespeare

plainsong

/ (ˈpleɪnˌsɒŋ) /

the style of unison unaccompanied vocal music used in the medieval Church, esp in Gregorian chant Also called: plainchant

C16: translation of Medieval Latin cantus plānus