accelerando
A gradual increase in tempo.
In Depth
Accelerando is one of the most common tempo changes in music. Composers use it to build excitement or drive toward a climax, and it appears in everything from symphonies to film scores. The marking is often abbreviated as accel. in sheet music.
In practice, a good accelerando feels natural rather than mechanical. Performers must coordinate carefully in ensemble playing to speed up together. Beethoven and Rossini were particularly fond of using accelerando to create dramatic tension in their orchestral works.
Rossini used accelerando so often in his operas that the technique became known as the Rossini crescendo, though it combines speeding up with getting louder.