Which term describes a gradual increase in loudness?

The term that describes a gradual increase in loudness is crescendo. A crescendo is a dynamic indication in music performance, often notated in the sheet music to guide musicians on how to gradually raise the volume of the sound. This technique is utilized to create a sense of building intensity and can be effective in conveying emotions, heightening tension, or leading into a climactic moment in a piece of music.

On the contrary, diminuendo refers to a gradual decrease in loudness, while staccato describes a style of playing notes in a detached manner, and legato refers to playing notes smoothly and connectedly. These terms speak to different aspects of musical performance and dynamics, clearly distinguishing crescendo as the term specifically associated with an increase in volume.