plainsong

noun4

1. •
   A form of monophonic chant in unison using the Gregorian scale, sung in various Christian churches.
2. •
   The simple notes of an air, without ornament or variation.
3. •
   A cantus firmus or theme chosen for contrapuntal treatment; so called because often an actual fragment of plain-song.
4. •
   A plain unvarnished statement, without exaggeration.