Which term refers to a highly structured, imitative contrapuntal composition in which a single theme prevails?

The term that refers to a highly structured, imitative contrapuntal composition in which a single theme prevails is a fugue. A fugue starts with the presentation of a main theme, known as the subject, which is then imitated by other voices in a gradually unfolding complexity. This interplay creates a rich texture as multiple voices engage in a dialogue based on the original theme. The form is characterized by its rigorous structure, typically involving the exposition of the subject followed by episodes that explore related material. This makes the fugue not only a demonstration of contrapuntal skill but also a profound expression of thematic development.

In contrast, a passacaglia is a form based on a repeated bass line or harmonic progression, whereas a suite is a collection of contrasting movements or dances, and a chorale is usually a hymn tune in the context of liturgical music, focusing more on the melody rather than the intricate polyphonic texture seen in a fugue. Each of these forms has its own unique characteristics that set them apart from the imitative and thematically driven nature of a fugue.