attain vs average

attain is not a noun while average is a noun.

Word	Noun	Adjective	Verb	Adverb
attain	No	No	Yes	No
average	Yes	Yes	Yes	No

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

Other hyponyms of attain include score, get to, make, progress to, reach, begin, come to, strike, culminate, compass, finagle, manage, wangle.

attain (noun)	average (noun)
	a statistic describing the location of a distribution
	an intermediate scale value regarded as normal or usual
	(sports) the ratio of successful performances to opportunities

attain (adjective)	average (adjective)
	lacking special distinction, rank, or status; commonly encountered
	around the middle of a scale of evaluation
	lacking exceptional quality or ability
	relating to or constituting the middle value of an ordered set of values (or the average of the middle two in a set with an even number of values)
	approximating the statistical norm or average or expected value
	relating to or constituting the most frequent value in a distribution

attain (verb)	average (verb)
reach a point in time, or a certain state or level	compute the average of
reach a destination, either real or abstract	achieve or reach on average
find unexpectedly	amount to or come to an average, without loss or gain
to gain with effort