betterment vs melioration

betterment and melioration both are nouns.

Word	Noun	Adjective	Verb	Adverb
betterment	Yes	No	No	No
melioration	Yes	No	No	No

As nouns, betterment and melioration are synonyms defined as:

betterment and melioration: the act of relieving ills and changing for the better

Other synonyms of betterment include amelioration.

As nouns, melioration is a hypernym of betterment; that is, melioration is a word with a broader meaning than betterment:

Other hypernyms of betterment include improvement.

betterment (noun)	melioration (noun)
the act of relieving ills and changing for the better	the act of relieving ills and changing for the better
a change for the better; progress in development	the linguistic process in which over a period of time a word grows more positive in connotation or more elevated in meaning
an improvement that adds to the value of a property or facility	a condition superior to an earlier condition