Noun
An organ or instrument; hence, a method by which philosophical or scientific investigation may be conducted; -- a term adopted from the Aristotelian writers by Lord Bacon, as the title ("Novum Organon") of part of his treatise on philosophical method.
Source: Webster's dictionaryHe united this style with measured discant passages, which used the rhythmic modes to create the pinnacle of organum composition. Source: Internet
The motet probably arose from clausula sections, usually strophic interludes, in a longer sequence of organum, to which upper voices were added. Source: Internet
Over the next several centuries, organum developed in several ways. Source: Internet
The most significant of these developments was the creation of "florid organum" around 1100, sometimes known as the school of St. Martial (named after a monastery in south-central France, which contains the best-preserved manuscript of this repertory). Source: Internet
The motet took a definite rhythm from the words of the verse, and as such appeared as a brief rhythmic interlude in the middle of the longer, more chantlike organum. Source: Internet
This final stage of organum is sometimes referred to as Notre Dame school of polyphony, since that was where Léonin (and his student Pérotin ) were stationed. Source: Internet