1.Definition: a quantity added (e.g. to make up for a deficiency)

Related Noun(s):supplementation

Category: General

2.Definition: a supplementary component that improves capability

Related Noun(s):accessory, appurtenance

Category: Objects

3.Definition: textual matter that is added onto a publication; usually at the end

Related Noun(s):addendum, postscript

Category: General