Which term refers to something that is leftover or remaining?

The term "residual" specifically denotes something that remains after the greater part has been removed, used, or dealt with. It originates from the Latin word "residuum," meaning what is left behind. In various contexts, such as in finance or environmental science, "residual" conveys the idea of something that persists after a primary element has been addressed.

For example, in mathematics, a residual can denote the part of an observation that does not explain variance in a model, while in the context of waste management, it can refer to the leftover material after the disposal or recycling process. This precise meaning aligns with the definition of leftover or remaining, making it the most suitable choice in this context.

The other options each describe related but distinct concepts. "Surplus" refers to an amount that is more than what is needed or required; "excess" similarly indicates an overabundance. "Remaining" might seem fitting at first but is usually used more broadly to describe something still present rather than specifically focusing on what is left after significant removal. Therefore, "residual" accurately captures the notion of something distinctly left over.