medevac vs evacuation

medevac and evacuation both are nouns.

Word	Noun	Adjective	Verb	Adverb
medevac	Yes	No	No	No
evacuation	Yes	No	No	No

As nouns, evacuation is a hypernym of medevac; that is, evacuation is a word with a broader meaning than medevac:

medevac: the evacuation of persons (usually by air transportation) to a place where they can receive medical care
evacuation: the act of evacuating; leaving a place in an orderly fashion; especially for protection

medevac (noun)	evacuation (noun)
the evacuation of persons (usually by air transportation) to a place where they can receive medical care	the act of removing the contents of something
	the act of evacuating; leaving a place in an orderly fashion; especially for protection
	the bodily process of discharging waste matter