cholera morbus vs stomach flu

cholera morbus and stomach flu both are nouns.

Word	Noun	Adjective	Verb	Adverb
cholera morbus	Yes	No	No	No
stomach flu	Yes	No	No	No

As nouns, stomach flu is a hypernym of cholera morbus; that is, stomach flu is a word with a broader meaning than cholera morbus:

cholera morbus: severe gastroenteritis of unknown etiology; characterized by severe colic and vomiting and diarrhea
stomach flu: inflammation of the stomach and intestines; can be caused by Salmonella enteritidis

Other hypernyms of cholera morbus include gastroenteritis, intestinal flu.

cholera morbus (noun)	stomach flu (noun)
severe gastroenteritis of unknown etiology; characterized by severe colic and vomiting and diarrhea	inflammation of the stomach and intestines; can be caused by Salmonella enteritidis