A semantic change toward a more positive connotation in the meaning of a word or morpheme; for example, the English word nice, which meant "foolish" in Middle English, now means kind or pleasant. Other examples of amelioration include the elevation of the Latin word casa ‘hut, cottage' to Modern Spanish casa ‘house,' and the change in meaning of Old English cniht ‘boy, servant' to Modern English knight (Campbell p.63).

The act of ameliorating, or the state of being ameliorated; making or becoming better; improvement; melioration.

the act of relieving ills and changing for the better

Making or becoming better (ie. improvement in ecosystem function).

"Ameliorate" means to make less severe or to improve. Impact amelioration proposals suggest ways to avoid or lessen the negative effects of a project on the environment

Poison length reduced by 50

Adjustment or correction of a wine must before fermentation, usually referring to addition of sugar or acid where lacking in the original fruit.