rarefied vs high-flown

rarefied and high-flown both are adjectives.

Word	Noun	Adjective	Verb	Adverb
rarefied	No	Yes	No	No
high-flown	No	Yes	No	No

As adjectives, rarefied and high-flown are synonyms defined as:

rarefied and high-flown: of high moral or intellectual value; elevated in nature or style

Other synonyms of rarefied include elevated, exalted, grand, high-minded, idealistic, lofty, noble-minded, rarified, sublime.

rarefied (adjective)	high-flown (adjective)
of high moral or intellectual value; elevated in nature or style	of high moral or intellectual value; elevated in nature or style
having low density	pretentious (especially with regard to language or ideals)