fantasia
A free-form composition that follows the composer's imagination rather than a strict formal pattern
In Depth
The fantasia has existed since the Renaissance, always defined by its freedom from structural convention. Renaissance fantasias explored imitative counterpoint freely; Baroque fantasias alternated between improvisatory passages and strict fugal writing; Romantic fantasias could be large-scale narrative works. The common thread is spontaneity — the sense that the music unfolds according to the moment rather than a predetermined plan. Mozart's, Chopin's, and Schumann's fantasias rank among the great works of the repertoire.
Mozart's Fantasia in D minor, K. 397, breaks off abruptly in some editions because the ending was either lost or never completed — scholars still debate which.