What is the term for music that should be played with a strong, firm tone?

The term that signifies music should be played with a strong, firm tone is "forte." In musical notation, forte is indicated by the symbol "f" and instructs the performer to play loudly and with intensity, reflecting an energetic or powerful expression. This is crucial as it directly impacts the emotional delivery and overall dynamics of a piece.

In contrast, the other terms have different meanings: "grazioso" refers to a graceful and elegant style, "crescendo" indicates a gradual increase in volume, and "legato" denotes a smooth, connected manner of playing. Understanding the distinction between these dynamics enriches a performer’s interpretation and execution of music.