Which term is used to describe music that is gradually getting louder?

The term that describes music that is gradually getting louder is "crescendo." In musical notation, a crescendo is often indicated by a symbol that looks like a long, thin angle gradually widening, suggesting an increase in volume. This technique is used to create a sense of build-up or intensity in a piece of music, enhancing the emotional impact of the performance.

In contrast, "forte" refers to music played loudly, but it denotes a static dynamic level rather than a gradual increase. Meanwhile, "piano" indicates soft dynamics, and "diminuendo" refers to a gradual decrease in volume. Therefore, "crescendo" is the precise term for music that progressively gets louder, differentiating it from these other musical dynamics.