Which term refers to an amount of something left over after requirements have been met?

The term that best refers to an amount of something left over after requirements have been met is "surplus." In various contexts, including economics and resource management, a surplus indicates that there is more of a resource available than is necessary or required. For example, in financial terms, if a budget exceeds the necessary expenditures, the remaining funds are considered a surplus.

Although other terms may seem relevant, they don’t convey the precise meaning in this context. "Excess" generally refers to something that is more than what is needed but doesn’t imply a leftover amount after needs are fulfilled. "Overflow" implies that something is spilling over or exceeding capacity, which is distinct from simply having an amount left over. "Residual" refers to what remains after a process or event, but it often implies a leftover that may not be usable or desirable, differentiating it from the more positive connotation of a surplus. Thus, in identifying an amount left over after needs have been satisfied, "surplus" is the most appropriate term.