Which musical term denotes a slowing down or a less intense passage?

The term that denotes a slowing down or a less intense passage is "rallentando." This word comes from Italian, meaning “relaxing” or “slowly.” It instructs the performer to gradually decrease the tempo, often leading to a more relaxed or serene musical moment. This technique is typically utilized to create a contrast with sections played at a faster pace, heightening the emotional impact of the music by allowing it to breathe and resonate.

In the context of the other choices, "accelerando" refers to a gradual increase in speed, resulting in a sense of urgency or forward motion, which opposes the concept of slowing down. "Affrettando" also indicates a quickening of tempo, suggesting an urgent or hurried manner. "Espressivo," on the other hand, directs the performer to play expressively or with emotion but does not specify changes in speed or intensity.

Therefore, "rallentando" is the appropriate term to describe a passage characterized by a slowing down or a decrease in musical intensity.