The word 剩余 is formed through a logical, meaning-based combination of two independent characters: 剩, which carries the core idea of "leaving over" or "being surplus", and 余, which reinforces this by meaning "extra" or "remainder". By placing them side-by-side, they create a single, cohesive concept where the meaning of the second character (余) specifically defines and clarifies the nature of what is left over from the first (剩), resulting in the combined meaning of "that which remains" or "surplus".