rationalise away vs reason

rationalise away is not a noun while reason is a noun.

Word	Noun	Adjective	Verb	Adverb
rationalise away	No	No	Yes	No
reason	Yes	No	Yes	No

As verbs, reason is a hypernym of rationalise away; that is, reason is a word with a broader meaning than rationalise away:

rationalise away (noun)	reason (noun)
	the capacity for rational thought or inference or discrimination
	a fact that logically justifies some premise or conclusion
	a justification for something existing or happening
	an explanation of the cause of some phenomenon
	a rational motive for a belief or action
	the state of having good sense and sound judgment

rationalise away (verb)	reason (verb)
substitute a natural for a supernatural explanation of	think logically
	decide by reasoning; draw or come to a conclusion
	present reasons and arguments