rhapsody
A wild, emotional piece of music that feels very free.
A rhapsody is a piece of music that feels wild, free, and full of emotion. Unlike a carefully structured symphony, a rhapsody flows wherever the composer's feelings take it, jumping from quiet, dreamy passages to dramatic, stormy sections without warning. George Gershwin's famous Rhapsody in Blue swings between jazzy piano riffs and sweeping orchestral melodies, capturing the energy of 1920s New York City.
Composers write rhapsodies when they want to express powerful feelings without following strict rules about form or structure.
You might also hear people use rhapsody to describe someone speaking with extreme enthusiasm. If your friend goes into rhapsodies about their favorite book series, they're gushing about it with unstoppable excitement. To rhapsodize means to talk or write about something with that same passionate, flowing energy, like when someone can't stop describing every detail of an amazing vacation.