Definitions
1.NounSomething that, or someone who, improves something.
2.NounSpecifically, a person who improves land or property, a landscaper.
3.NounOne who improves his or her performance, one who shows improvement (of individuals or groups).
4.NounA substance added to cause improvement (especially to a foodstuff).
5.NounA pad worn by women to make the dress hang properly.
6.NounOne who performs improv; an improviser.