amelioration

1. The act or an instance of ameliorating.
2. The state of being ameliorated; improvement.

noun

1. The act of making better or the condition of being made better: amendment, betterment, improvement, melioration, upgrade. See better/worse.
2. Steady improvement, as of an individual or a society: betterment, development, improvement, melioration, progress. See better/worse.

Definition: improvement
Antonyms: worsening

[uh-MEEL-yuh-RAY-shuhn] A catchall term for various methods of improving a wine, some of which are illegal in commercial winemaking. These methods include adding sugar, water, and/or acid to the grape juice or wine to correct deficiencies. Most countries have regulations pertaining to these practices with regard to commercial winemaking.

The noun has one meaning:

Meaning #1: the act of relieving ills and changing for the better
  Synonyms: melioration, betterment