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, medieval, 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).
contemporary is likely to apply to people and what relates to them.
Abraham Lincoln was contemporary with Charles Darwin
contemporaneous is more often applied to events than to people.
contemporaneous accounts of the kidnapping
coeval refers usually to periods, ages, eras, eons.
two stars thought to be coeval
synchronous implies exact correspondence in time and especially in periodic intervals.
synchronous timepieces
simultaneous implies correspondence in a moment of time.
the two shots were simultaneous
coincident is applied to events and may be used in order to avoid implication of causal relationship.
the end of World War II was coincident with a great vintage year
Example Sentences
two stars thought to be coeval because they have nearly the same mass and brightness
Recent Examples on the WebHer letters to Bradley demonstrate that the idea was coeval with her wish to be a poet and her discovery of romantic feeling for girls, and that it was fully formed as early as her adolescence. Langdon Hammer, The New York Review of Books, 25 Feb. 2020 Tribalism and clannishness are coeval with human social life. Stephen Holmes, The New York Review of Books, 17 Jan. 2019
Word History
Etymology
Latin coaevus, from co- + aevum age, lifetime — more at aye