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1. Add as a supplement to what seems insufficient
   "supplement your diet"
    
2. Serve as a supplement to
   "Vitamins supplemented his meagre diet"
    
3. Add to the very end
   "He supplemented a glossary to his novel where he used an invented language";
   - append, add on, affix

1. Textual matter that is added onto a publication; usually at the end
   - addendum, postscript
    
2. A quantity added (e.g. to make up for a deficiency)
   - supplementation
    
3. A supplementary component that improves capability
   - accessory, appurtenance, add-on, bolt-on
    
4. (geometry) an angle that, when added to a given angle, makes 180 degrees

Derived forms: supplementing, supplemented, supplements

Type of: add, attach, be, component, comprise, constituent, constitute, element, increase, increment, make up, matter, represent

Part of: back matter, end matter

Encyclopedia: Supplement