These words refer to taking the measure of something large or small in quantity or degree, or in a plane or solid space. Size is the most general, being applicable in all these situations: a country of great size ; a small watermelon the size of your head; the size of the city’s population; the size of the rate increase. By contrast, area and expanse restrict themselves most specifically to surface measurements. Area is most often used in neutral description or to focus attention on a particular region: pinpointing areas of discontent in South-East Asia; a small area of tenderness just behind the left ear. Expanse suggests a larger space than area : an expanse of virgin timberlands; an inflamed expanse of skin across his chest and stomach. Area is also used to indicate a certain portion of an abstract whole: an often overlooked area of anthropological research.

Volume , bulk and mass all specifically refer to three-dimensional spaces. Volume may be used in indicating the exact amount of cubic space something takes up or the exact quantity needed to fill a container: a room with a volume of a thousand cubic feet; estimating the volume of water needed to fill the pool. It is used also for amplitude of sound and arbitrarily for some other measurements: an increasing volume of trunk calls per annum. By contrast, bulk does not suggest exactness of measure, but does refer to a considerable size that may not be proportionate to its weight: breakfast food packages of deceptive bulk . The word has a special use for indicating a major portion: taking on the bulk of the work himself. In scientific usage, mass refers to a quantification of matter underlying gravity and weight. In ordinary use, the word emphasizes weight, density or quantity, and may specifically suggest a large bulk of uneven outline: masses of debris left from the explosion. Less specifically, it may suggest a great amount: a mass of exam papers to correct and mark.

Extent and scope both may be used to indicate linear or plane distances like area or more generally to indicate degree. In surface measurement, extent suggests an effort to determine the distance something reaches to, especially a linear distance that is subject to change: estimating the extent of river made brackish by the backing up of salt water from the ocean; reports on the extent of the newly captured territory. Used to indicate degree, it is more flexible in application but less specific in meaning, only vaguely suggesting a metaphor of physical penetration: the extent to which he had made a study of structural grammar. Whereas extent implies a linear distance, scope implies a two-dimensional area that something has mastered or controls: bulletins on the scope of the flood’s destructiveness. Much more commonly, scope is used figuratively to indicate degree of mastery or breadth of concern: a book of immense-range and scope ; the extent of his reach; the scope of his mind.