What is a defining characteristic of Gregorian chants?

The defining characteristic of Gregorian chants is that they are performed in a monophonic and unaccompanied style. This means that the music consists of a single melodic line without any harmonic support or accompaniment. Gregorian chant emerged as a form of liturgical music in the Christian church during the Middle Ages, around the 9th and 10th centuries, and is known for its solemn, meditative quality, which aligns closely with the spiritual and liturgical context in which it was used.

The unaccompanied nature and simplicity of the melody enable it to convey a sense of purity and directness, enhancing its role in worship and prayer. Unlike later forms of music that often incorporate harmony and intricate arrangements, Gregorian chants focus on a singular melodic line, making them distinct in their style and function within the history of Western music.