heterocycle vs closed chain

heterocycle and closed chain both are nouns.

Word	Noun	Adjective	Verb	Adverb
heterocycle	Yes	No	No	No
closed chain	Yes	No	No	No

As nouns, closed chain is a hypernym of heterocycle; that is, closed chain is a word with a broader meaning than heterocycle:

heterocycle: a ring of atoms of more than one kind; especially a ring of carbon atoms containing at least one atom that is not carbon
closed chain: (chemistry) a chain of atoms in a molecule that forms a closed loop

Other hypernyms of heterocycle include ring.

heterocycle (noun)	closed chain (noun)
a ring of atoms of more than one kind; especially a ring of carbon atoms containing at least one atom that is not carbon	(chemistry) a chain of atoms in a molecule that forms a closed loop
a compound containing a heterocyclic ring