Other forms: ameliorations
Amelioration is a process that makes something better. A philanthropist might devote her life to the amelioration of poverty and hunger.
Any time there's amelioration, something negative is becoming more positive. If your landlord improves the water pressure and lowers the rent, that's amelioration. Often this word has to do with words themselves and how some change in meaning over the years, becoming more positive. A good example is terrific, which once meant "causing terror" and now means "wonderful" or "awesome." Through amelioration, terrific went from a negative meaning to a positive one.