textual matter that is added onto a publication; usually at the end

同义词：addendum??/??postscript

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

同义词：supplementation

a supplementary component that improves capability

同义词：accessory??/??appurtenance??/??add-on

add as a supplement to what seems insufficient

serve as a supplement to

add to the very end

同义词：append??/??add on??/??affix