supplement supplement /ˌsəpləˈmɛnt/

noun

1. () A supplementary component that improves capability  ( add-on , appurtenance , bolt-on , accessory , supplement )
   a supplementary component that improves capability
   
2. () A quantity added (e.g. to make up for a deficiency)  ( supplementation , supplement )
   a quantity added (e.g. to make up for a deficiency)
     The supplement provided essential nutrients for overall health.
   The supplement provided essential nutrients for overall health.
   
3. () Textual matter that is added onto a publication; usually at the end  ( addendum , postscript , supplement )
   textual matter that is added onto a publication; usually at the end
   

verb

1. () Add as a supplement to what seems insufficient  ( supplement )
   add as a supplement to what seems insufficient
    Supplement your diet
   supplement your diet
   
2. Add to the very end  ( add on , supplement , append , affix )
   add to the very end
    He appended a glossary to his novel where he used an invented language
   He appended a glossary to his novel where he used an invented language
   
3. Serve as a supplement to  ( supplement )
   serve as a supplement to
    Vitamins supplemented his meager diet
   Vitamins supplemented his meager diet