approximate vs put

approximate is not a noun while put is a noun.

Word	Noun	Adjective	Verb	Adverb
approximate	No	Yes	Yes	No
put	Yes	No	Yes	No

As verbs, put is a hyponym of approximate; that is, put is a word with a more specific, narrower meaning than approximate:

approximate (noun)	put (noun)
	the option to sell a given stock (or stock index or commodity future) at a given price before a given date

approximate (verb)	put (verb)
judge tentatively or form an estimate of (quantities or time)	arrange thoughts, ideas, temporal events
be close or similar	estimate
	formulate in a particular style or language
	attribute or give
	put into a certain place or abstract location
	cause to be in a certain state; cause to be in a certain relation
	adapt
	cause (someone) to undergo something
	make an investment