The term describes a subtle and gradual decrease in tempo within a musical composition. The Italian word “poco” signifies “a little,” modifying “rallentando,” which indicates a slowing down. Therefore, the instruction directs performers to implement a slight and progressive reduction in speed, creating a gentle deceleration. An example would be a performer noticing “poco rallentando” written over the final two measures of a piece, signaling a very slight easing of the tempo leading to the final note.
This direction is crucial for expressive performance. It allows for the creation of subtle nuances and emotional impact. It can emphasize the conclusion of a phrase, heighten suspense, or signal a transition to a new section. Historically, this notation and similar tempo modifications have been employed by composers to guide performers in interpreting their works, providing instructions beyond simply the notes and rhythms on the page. These markings allow a performer to execute a musical piece with greater nuance and impact.