Definition of "Supplement" :

noun: a supplementary component that improves capability

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

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

verb: add to the very end

verb: add as a supplement to what seems insufficient

"Supplement your diet."

verb: serve as a supplement to

"Vitamins supplemented his meager diet."