The word 发抖 is formed by combining two characters whose individual meanings visually and conceptually merge to create a new idea. 发 (fā) carries a sense of emitting or sending out, while 抖 (dǒu) specifically depicts a rapid, shaking motion. Together, they create a direct, almost kinetic image of the body "emitting shakes" or "sending out tremors", perfectly capturing the physical phenomenon of trembling.