'Melioration' definitions:

Definition of 'melioration'

From: WordNet
noun
The act of relieving ills and changing for the better [syn: amelioration, melioration, betterment]
noun
A condition superior to an earlier condition; "the new school represents a great improvement" [syn: improvement, melioration] [ant: declination, decline]
noun
The linguistic process in which over a period of time a word grows more positive in connotation or more elevated in meaning

Definition of 'Melioration'

From: GCIDE
  • Melioration \Mel`io*ra"tion\, n. [L. melioratio.] The act or operation of meliorating, or the state of being meliorated; improvement. --Bacon. [1913 Webster]