fourth stomach vs breadbasket

fourth stomach and breadbasket both are nouns.

Word	Noun	Adjective	Verb	Adverb
fourth stomach	Yes	No	No	No
breadbasket	Yes	No	No	No

As nouns, breadbasket is a hypernym of fourth stomach; that is, breadbasket is a word with a broader meaning than fourth stomach:

fourth stomach: the fourth compartment of the stomach of a ruminant; the one where digestion takes place
breadbasket: an enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion

Other hypernyms of fourth stomach include stomach, tum, tummy.

fourth stomach (noun)	breadbasket (noun)
the fourth compartment of the stomach of a ruminant; the one where digestion takes place	a basket for serving bread
	an enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion
	a geographic region serving as the principal source of grain