microorganism vs monad

microorganism and monad both are nouns.

Word	Noun	Adjective	Verb	Adverb
microorganism	Yes	No	No	No
monad	Yes	No	No	No

As nouns, monad is a hyponym of microorganism; that is, monad is a word with a more specific, narrower meaning than microorganism:

microorganism: any organism of microscopic size
monad: (biology) a single-celled microorganism (especially a flagellate protozoan)

microorganism (noun)	monad (noun)
any organism of microscopic size	(biology) a single-celled microorganism (especially a flagellate protozoan)
	a singular metaphysical entity from which material properties are said to derive
	(chemistry) an atom having a valence of one