pyrimidine vs cytosine

pyrimidine and cytosine both are nouns.

Word	Noun	Adjective	Verb	Adverb
pyrimidine	Yes	No	No	No
cytosine	Yes	No	No	No

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

pyrimidine: any of several basic compounds derived from pyrimidine
cytosine: a base found in DNA and RNA and derived from pyrimidine; pairs with guanine

Other hyponyms of pyrimidine include C, T, thymine.

pyrimidine (noun)	cytosine (noun)
a heterocyclic organic compound with a penetrating odor	a base found in DNA and RNA and derived from pyrimidine; pairs with guanine
any of several basic compounds derived from pyrimidine