astronomy vs epoch

astronomy and epoch both are nouns.

Word	Noun	Adjective	Verb	Adverb
astronomy	Yes	No	No	No
epoch	Yes	No	No	No

astronomy (noun)	epoch (noun)
the branch of physics that studies celestial bodies and the universe as a whole	a period marked by distinctive character or reckoned from a fixed point or event
	a unit of geological time that is a subdivision of a period and is itself divided into ages
	(astronomy) an arbitrarily fixed date that is the point in time relative to which information (as coordinates of a celestial body) is recorded