add-on

/ˌæd ˈɑn/

/ˈædɒn/

Definitions of add-on

1. noun

   a supplementary component that improves capability
   synonyms: accessory, appurtenance, supplement

   types:

   auto accessory

   an accessory for an automobile

   computer accessory

   an accessory for a computer

   fitting

   a small and often standardized accessory to a larger system

   fixings, trimmings

   the accessories that normally accompany (something or some activity)

   gas fitting

   the fitting (pipes or valves or meters) that convey gas from the gas main to the gas fixtures of a building

   pipe fitting, pipefitting

   fitting consisting of threaded pieces of pipe for joining pipes together

   receptacle

   an electrical (or electronic) fitting that is connected to a source of power and equipped to receive an insert

   type of:

   component, constituent, element

   an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system
2. noun

   a component that is added to something to improve it
   synonyms: addition, improver

   types:

   additive

   something added to enhance food or gasoline or paint or medicine

   afterthought

   an addition that was not included in the original plan

   annex, annexe, extension, wing

   an addition that extends a main building

   attachment

   a supplementary part or accessory

   elongation, extension

   an addition to the length of something

   addendum

   a thing that is added or will be added

   adjuvant

   (medicine) a therapy, medicine, or anything that makes a medical treatment more effective or manageable

   ell

   an extension at the end and at right angles to the main building

   artificial additive, food additive

   an additive to food intended to improve its flavor or appearance or shelf-life

   hood, lens hood

   a tubular attachment used to keep stray light out of the lens of a camera

   type of:

   component, constituent, element

   an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system