"coterminous" is a perfectly acceptable word in written English and can be used in many contexts.
Coterminous typically means having the same boundaries or duration. For example, you could say, "The two organizations have coterminous goals for the upcoming year."
There is a serious, long-term questioning of the notion that Irish identity is coterminous with Catholicism.
A coterminous state election, in which Congress trounced the TDP, also had wider significance.
This is a domain so vast, vague and ancient that it is almost coterminous with politics itself.
Ms Pelosi's district, California's eighth, is more or less coterminous with San Francisco, the bluest, most liberal city in America.
Mount Whitney, highest peak (14,494 feet [4,418 metres] above sea level) in the 48 coterminous U.S. states.
There are levels of structure in each of the modes, and the units of one level are not necessarily coterminous with those of another.
The northeast is coterminous with the Khorat Plateau, a vast tableland bounded by the Mekong River on the north and east.
Only two of the Bantustans (Ciskei and Qwaqwa) had a totally coterminous land area; each of the others consisted of anywhere from 2 to 30 scattered blocks of land, some of them widely dispersed.
In 1892 the New York state legislature created Adirondack Park, which has grown over the years and is roughly coterminous with the Adirondacks region, making it the largest American state or national park outside of Alaska.
About 1965, roughly coterminous with the development of time-sharing, a new kind of computer came on the scene.
The setting for political philosophy thus became much wider, relating individuals to universal empire thought of, as in China, as coterminous with civilization itself.
