barium enema vs enema

barium enema and enema both are nouns.

Word	Noun	Adjective	Verb	Adverb
barium enema	Yes	No	No	No
enema	Yes	No	No	No

As nouns, enema is a hypernym of barium enema; that is, enema is a word with a broader meaning than barium enema:

barium enema: enema in which a contrast medium (usually barium sulfate) is injected into the rectum and X-rays are taken to search for lesions
enema: an injection of a liquid through the anus to stimulate evacuation; sometimes used for diagnostic purposes

Other hypernyms of barium enema include clyster.

barium enema (noun)	enema (noun)
enema in which a contrast medium (usually barium sulfate) is injected into the rectum and X-rays are taken to search for lesions	an injection of a liquid through the anus to stimulate evacuation; sometimes used for diagnostic purposes