What does the term "cantus firmus" refer to?

The term "cantus firmus" refers to a fixed song used as the basis for composition. In music, this is a significant concept primarily associated with the medieval and Renaissance periods. A cantus firmus typically consists of a pre-existing melody that serves as a foundational line over which additional voices or musical lines are composed. This technique allows composers to create complex polyphonic works while grounding them in a stable, recognizable melody.

The use of a cantus firmus can be seen in various forms, such as Gregorian chants, which were often adapted for polyphonic settings. By establishing a clear melodic line, the cantus firmus facilitates the integration of harmonic and contrapuntal elements, allowing composers to explore more intricate musical relationships. This approach has influenced countless works throughout music history, making it a vital element in the development of Western classical music.