plainsong
From Longman Dictionary of Contemporary EnglishRelated topics: Musicplainsongplain‧song /ˈpleɪnsɒŋ $ -sɒːŋ/ (also plainchant) noun [uncountable] APMa type of old Christian church music in which people sing a simple tune without musical instrumentsExamples from the Corpusplainsong• Most chanting is unaccompanied, often because no one is available with the required skill, especially to accompany plainsong.• They gather only for services of prayer and plainsong.