fugue

/ˈfjuːɡ/
noun
  1. 1

    A contrapuntal piece of music wherein a particular melody is played in a number of voices, each voice introduced in turn by playing the melody.

  2. 2

    Anything in literature, poetry, film, painting, etc., that resembles a fugue in structure or in its elaborate complexity and formality.

  3. 3

    A fugue state.

verb
  1. 1

    To improvise, in singing, by introducing vocal ornamentation to fill gaps etc.

Source: https://en.wiktionary.org/wiki/fugue