precaution vs precautionary

precaution is a noun but precautionary is not a noun.

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

precaution (noun)	precautionary (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

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