organum

noun

or·​ga·​num ˈȯr-gə-nəm 

1

: early polyphony of the late Middle Ages that consists of one or more voice parts accompanying the cantus firmus often in parallel motion at a fourth, fifth, or octave above or below

also : a composition in this style

2

: organon

Word History

Etymology

Medieval Latin, from Latin, organ

First Known Use

1620, in the meaning defined at sense 2