Coeval comes to English from the Latin word coaevus, meaning "of the same age." Coaevus was formed by combining the co- prefix ("in or to the same degree") with Latin aevum ("age" or "lifetime"). The root aevum is also a base in such temporal words as longevity , medieva l, and primeval . Although coeval can technically describe any two or more entities that coexist, it is most typically used to refer to things that have existed together for a very long time (such as galaxies) or that were concurrent with each other in the distant past (parallel historical periods of ancient civilizations, for example).

Examples

"Fantasy is at least as immense as realism and much older—essentially coeval with literature itself. Yet fantasy was relegated for fifty years or sixty years to the nursery." — Ursula Le Guin, quoted in Electric Literature, 1 Apr. 2016

"If animals are our other, there is nothing quite so other as the octopus. It is the alien with whom we share our planet, a coeval evolutionary life form whose slithery slipperiness and more than the requisite number of limbs … symbolize the dark mystery and fear of the deep." — Philip Hoare, The Guardian, 18 Sept. 2017