stomach vs pit of the stomach

stomach and pit of the stomach both are nouns.

Word	Noun	Adjective	Verb	Adverb
stomach	Yes	No	Yes	No
pit of the stomach	Yes	No	No	No

stomach (noun)	pit of the stomach (noun)
an enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion	a slight depression in the midline just below the sternum (where a blow can affect the solar plexus)
the region of the body of a vertebrate between the thorax and the pelvis
an appetite for food
an inclination or liking for things involving conflict or difficulty or unpleasantness

stomach (verb)	pit of the stomach (verb)
put up with something or somebody unpleasant
bear to eat