cautionary vs prophylactic

cautionary is not a noun while prophylactic is a noun.

Word	Noun	Adjective	Verb	Adverb
cautionary	No	Yes	No	No
prophylactic	Yes	Yes	No	No

As adjectives, cautionary and prophylactic are synonyms defined as:

cautionary (noun)	prophylactic (noun)
	contraceptive device consisting of a sheath of thin rubber or latex that is worn over the penis during intercourse
	remedy that prevents or slows the course of an illness or disease

cautionary (adjective)	prophylactic (adjective)
serving to warn	preventing or contributing to the prevention of disease
warding off	warding off
	capable of preventing conception or impregnation