colonic irrigation vs clyster

colonic irrigation and clyster both are nouns.

Word	Noun	Adjective	Verb	Adverb
colonic irrigation	Yes	No	No	No
clyster	Yes	No	No	No

As nouns, clyster is a hypernym of colonic irrigation; that is, clyster is a word with a broader meaning than colonic irrigation:

colonic irrigation: a water enema given to flush out the colon
clyster: an injection of a liquid through the anus to stimulate evacuation; sometimes used for diagnostic purposes

Other hypernyms of colonic irrigation include enema.

colonic irrigation (noun)	clyster (noun)
a water enema given to flush out the colon	an injection of a liquid through the anus to stimulate evacuation; sometimes used for diagnostic purposes