The word "忙碌" is formed by combining two characters, each contributing a layer of meaning to create a unified concept. The first character, "忙", directly means "busy" or "hurried", setting the core theme. The second character, "碌", on its own, evokes the image of a stone roller grinding grain, a symbol of continuous, repetitive, and laborious motion. When paired together, "碌" doesn't just repeat "busy"; it deepens it, painting a picture of a bustling, ceaseless activity, like the constant turning of a millstone. Thus, the formation visually and conceptually stacks the idea of being "busy" atop the notion of "relentless toil" to express a state of being fully and actively occupied.