supplement
noun
textual matter that is added onto a publication; usually at the end
a quantity added (e.g. to make up for a deficiency)
Synonymssupplementationa supplementary component that improves capability
verb
add as a supplement to what seems insufficient
“supplement your diet”
serve as a supplement to
“Vitamins supplemented his meager diet”
add to the very end
“He appended a glossary to his novel where he used an invented language”
Source: WordNet 3.1, Princeton University
