extent

Extent is a noun and verb that refers to the size, scope, or reach of something, as well as to the action of spreading or stretching. It conveys how large, wide, long, or significant a thing is, and can apply to physical space, time, or degree. The word derives from Latin extentus, meaning stretched out.

In geography and cartography, extent denotes the geographic area covered by a region or displayed on a map. The geographic extent of a country is its land area, while a map’s extent defines the boundaries visible within the projection. The term also describes the spatial range of habitats, ecosystems, or phenomena such as the extent of a forest or a drought.

In science and astronomy, extent can refer to the angular size of an object in the sky (its apparent size) or to its actual physical size. For example, the angular extent of a galaxy describes how large it appears from Earth, while the physical extent relates to its true dimensions. In ecological and environmental contexts, extent is used to describe how far a phenomenon, such as a wildfire or pollution, has spread.

In law, policy, and everyday usage, extent indicates the breadth of applicability or influence. Phrases like “to the extent possible” or “the extent of liability” relate to the degree or scope to which a rule, obligation, or effect applies.

Overall, extent is a flexible term used across disciplines to express how much or how far something reaches, with meaning anchored by context.