Definitions

1. noun

a type of monophonic sacred music, especially Gregorian chant, sung in a simple, unaccompanied style

“The choir performed a beautiful plainsong rendition of the hymn during the church service.”

2. noun

a type of folk song, especially in the British Isles, that is characterized by its simple, unaccompanied style

“The ballad singer specialized in performing traditional plainsongs from her native Scotland.”