organumPronunciation: /ˈɔːg(ə)nəm/Definition of organum noun (plural organa /-nə/) an early type of polyphonic music based on plainsong with an accompaniment sung below or above the melody. a part sung as an accompaniment below or above a melody. Origin:Latin, from Greek organon, literally 'instrument, organ'organum in other Oxford dictionaries Definition of organum in the US English dictionary
