clyster vs barium enema

clyster and barium enema both are nouns.

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

As nouns, barium enema is a hyponym of clyster; that is, barium enema is a word with a more specific, narrower meaning than clyster:

clyster: an injection of a liquid through the anus to stimulate evacuation; sometimes used for diagnostic purposes
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

Other hyponyms of clyster include colonic, colonic irrigation.

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