1728, "to make better," in some cases perhaps a back-formation from amelioration on pattern of French améliorer, or else from Medieval Latin amelioratus, past participle of ameliorare. The intransitive sense of "grow better" is by 1789. The simpler form meliorate was used in Middle English. Related: Ameliorated; ameliorating; ameliorable.
updated on September 19, 2022