approximate vs calculate

approximate is an adjective but calculate is not an adjective.

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

As verbs, calculate is a hypernym of approximate; that is, calculate is a word with a broader meaning than approximate:

Other hypernyms of approximate include cipher, compute, cypher, figure, reckon, work out.

approximate (verb)	calculate (verb)
judge tentatively or form an estimate of (quantities or time)	make a mathematical calculation or computation
be close or similar	specifically design a product, event, or activity for a certain public
	judge to be probable
	have faith or confidence in
	predict in advance
	keep an account of