Notre dame organum
DEFINITION
A polyphonic composition based on plainchant in which the new voice(s) appears above the original voice; Notre Dame organum is the most elaborate style of organum, incorporating rhythmic passages and elaborate melismas in the new voices. It originated during the late twelfth century in Paris. See organum, organum purum, copula, discant (2), Magnus Liber, rhythmic modes, substitute clausula.