small intestine vs gut

small intestine and gut both are nouns.

Word	Noun	Adjective	Verb	Adverb
small intestine	Yes	No	No	No
gut	Yes	No	Yes	No

As nouns, gut is a hypernym of small intestine; that is, gut is a word with a broader meaning than small intestine:

small intestine: the longest part of the alimentary canal; where digestion is completed
gut: the part of the alimentary canal between the stomach and the anus

Other hypernyms of small intestine include bowel, intestine.

small intestine (noun)	gut (noun)
the longest part of the alimentary canal; where digestion is completed	a strong cord made from the intestines of sheep and used in surgery
	the part of the alimentary canal between the stomach and the anus
	a narrow channel or strait

small intestine (verb)	gut (verb)
	remove the guts of
	empty completely; destroy the inside of