an act of improving or the state of being improved.
Definition: 2
a change or addition by which a thing is improved.
Definition: 3
a person or thing that represents an advance on another in excellence or achievement: The new landlord is a great improvement over his greedy predecessor.
Definition: 4
a bringing into a more valuable or desirable condition, as of land or real property; betterment.
Definition: 5
something done or added to real property that increases its value.