What is the mathematical term for the space within a set of boundaries on a flat surface?

Area refers to the amount of space enclosed within a set of boundaries on a flat surface. It is measured in square units and represents the two-dimensional extent of a shape, such as a rectangle, triangle, or circle. To calculate the area, different formulas are used depending on the geometric shape in question.

Perimeter, on the other hand, is the total distance around a shape and does not express the size of the flat surface itself; rather, it defines the boundary. Volume measures the amount of space occupied by a three-dimensional object and is not applicable in the context of a flat surface. Dimension generally refers to the measurable extent of an object in one direction (length, width, height) but does not specifically denote the space contained within boundaries. Therefore, the most suitable term for the space within set boundaries on a flat surface is area.