Supplements

Definition:
Noun:
Constituent | a supplementary component that improves capability
Increase | a quantity added (e.g. to make up for a deficiency)
Matter | textual matter that is added onto a publication; usually at the end
Verb:
Add | add as a supplement to what seems insufficient
Attach | add to the very end
Make up | serve as a supplement to

Synonyms:
Noun:
Constituent | accessory | add-on | appurtenance
Increase | supplementation
Matter | addendum | postscript
Verb:
Attach | add on | affix | append

Narrower terms:
Annex  |  appendix  |  auto accessory  |  computer accessory  |  continuation  |  eke out  |  fill out  |  fitting  | fixings | leverage | sequel |  trimmings | vitaminise | vitaminize

Broader terms:
Add  |  attach  |  be  |  component  |  comprise  |  constituent  |  constitute  |  element  |  increase  |  increment  |  make up  |  matter  |  represent