coeval vs synchronous

coeval is a noun but synchronous is not a noun.

Word	Noun	Adjective	Verb	Adverb
coeval	Yes	Yes	No	No
synchronous	No	Yes	No	No

coeval (noun)	synchronous (noun)
a person of nearly the same age as another

coeval (adjective)	synchronous (adjective)
of the same period	occurring or existing at the same time or having the same period or phase
	(digital communication) pertaining to a transmission technique that requires a common clock signal (a timing reference) between the communicating devices in order to coordinate their transmissions