A more thorough explanation:

Definition: Residuum refers to the remaining part of something after some parts have been removed or used up. It can also refer to the remaining part of an estate after all debts and bequests have been paid.

Examples:

• After making a cup of coffee, the grounds left in the filter are the residuum.
• When someone dies, their estate is divided among their heirs, but the residuum is what is left after all debts and bequests have been paid.

The first example illustrates how residuum refers to the remaining part of something. In this case, the coffee grounds are what is left after the liquid has been extracted. The second example illustrates how residuum refers to the remaining part of an estate. In this case, the residuum is what is left after all debts and bequests have been paid.