precautionary vs precaution

precautionary is not a noun while precaution is a noun.

Word	Noun	Adjective	Verb	Adverb
precautionary	No	Yes	No	No
precaution	Yes	No	No	No

precautionary (noun)	precaution (noun)
	a precautionary measure warding off impending danger or damage or injury etc.
	the trait of practicing caution in advance
	judiciousness in avoiding harm or danger

precautionary (adjective)	precaution (adjective)
taken in advance to protect against possible danger or failure