1. (noun)humanitarian, do-gooder, improver someone devoted to the promotion of humanwelfare and to social reforms
2. (noun)addition, add-on, improver a component that is added to something to improve it "the addition of a bathroom was a major improvement"; "the addition of cinnamon improved the flavor"
Definitions of 'improver'
Webster 1913 Dictionary
1. (noun)improver one who, or that which, improves
Definition of improver 
