Organum is defined as what type of music?

Organum is recognized as a style of medieval polyphony that involves taking a Gregorian chant—the monophonic and unaccompanied sacred music of the church—and adding one or more additional melodic lines to it. This technique developed during the early Middle Ages and marked an important evolution in Western music by moving from monophonic textures to polyphonic ones.

In organum, the original chant is usually presented in longer note values, while the added lines often move in parallel motion, creating a richer, more complex sound. This practice not only expanded the musical palette of the time but also laid the groundwork for more intricate forms of polyphony that would emerge later in the Renaissance. The historical and cultural context of organum illustrates its significance as an early structure upon which later musical styles were built.