S: (n) 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"
W: (v) add [Related to: addition] (bestow a quality on) "Her presence lends a certain cachet to the company"; "The music added a lot to the play"; "She brings a special atmosphere to our meetings"; "This adds a light note to the program"
W: (v) add on [Related to: add-on] (make an addition) "Let's add on to this"
W: (v) improve [Related to: improver] (to make better) "The editor improved the manuscript with his changes"