Which musical term describes a weighty or emphasized style?

The term that describes a weighty or emphasized style is "pesante." This term indicates a character of playing that conveys a sense of heaviness or gravity, often suggesting that the music should be performed in a bold, deliberate manner. In contrast, the other terms refer to different styles or articulations. "Piano" means soft, indicating a quieter dynamic; "leggero" suggests a light and delicate touch in performance; and "staccato" denotes a playing style where notes are played in a detached manner, creating a crisp and separated sound. Each of these terms highlights different expressive qualities in music, but pesante specifically communicates a sense of weight and emphasis, making it the correct choice in this context.