Definition

Noun: 1. A pre-existing melody, often taken from Gregorian chant, used as the structural foundation for a polyphonic composition (e.g., a mass or motet). Composers in the Medieval, Renaissance, and early Baroque periods would write new, intricate counterpoint around this fixed, slower-moving core melody.

Usage Examples

• Noun:
  • The composer built the entire mass around a cantus firmus derived from a popular secular song.
  • Identifying the cantus firmus is key to analyzing the structure of many Renaissance motets.
  • The tenor voice often carried the cantus firmus in early polyphonic works.

Advanced Usage

• Historical Technique: The use of a was a fundamental compositional technique from the 12th to the 17th centuries. It provided a coherent structural framework upon which complex polyphony could be constructed.
• Conceptual Extension: In modern musicology, the term can be used metaphorically to describe any recurring, foundational theme or idea that underpins a larger, more complex work.

Variants and Related Words

• Plural: The plural form is cantus firmi or, less commonly, cantus firmuses.
• Fixed Melody: This is a direct English synonym describing the function of a .
• Cantus (noun): In early music, can refer simply to a melody or vocal part, often the highest voice.

Synonyms

• Fixed melody
• Plainsong (when referring specifically to a Gregorian chant used as the basis)
• Structural melody
• Foundation melody

Related Idioms and Phrases

• To serve as a cantus firmus: Used figuratively to mean acting as the unchanging, foundational element within a changing context.
  • Example: In all his varied works, a concern for social justice serves as the cantus firmus.

Noun

1. a melody used as the basis for a polyphonic composition