coterminous

Coterminous is an adjective meaning having the same boundaries or extent as another entity. It is used in geography and politics to describe regions that share a boundary, or more generally to indicate that two or more areas coincide in space. The term can also apply in time, describing events, terms, or plans that occupy the same period.

Etymology and usage: Coterminous derives from Latin terminus end, with the prefix co- meaning together. It is often treated as interchangeable with conterminous in formal writing, though some style guides distinguish them for emphasis on shared borders (conterminous) or on identical extent (coterminous). Contiguous, by contrast, emphasizes adjacency rather than exact alignment of borders.

Typical usages: In geography, the coterminous United States refers to the 48 contiguous states, with Alaska and Hawaii not coterminous with them. The term is widely used to describe boundaries, jurisdictions, or districts whose extents precisely match. In temporal contexts, a schedule, term of office, or contract may be described as coterminous with another when they begin and end at the same time.