addition

/əˈdɪʃən/

/əˈdɪʃɪn/

Other forms: additions

An addition is the act of adding something new, like a baby — a new addition to your family — or what you do in math class: the addition of columns of numbers to get the sum.

The noun addition comes from the Old French word adition, meaning "that which is added." A new room built onto your house, a new item in a store's inventory, even another baseball cap in your collection — all of these are additions. Usually thought of as improvements, you may have heard the phrase "welcome addition" to describe a new cast mate to a television show that has lost its creative spark or a new ball field at your local park.

Definitions of addition

1. noun

   the arithmetic operation of summing; calculating the sum of two or more numbers
   synonyms: plus, summation

   type of:

   arithmetic operation

   a mathematical operation involving numbers
2. noun

   the act of adding one thing to another
   “the addition of flowers created a pleasing effect”

   “the addition of a leap day every four years”

   antonyms:

   subtraction

   the act of subtracting (removing a part from the whole)

   types:

   retrofit

   the act of adding a component or accessory to something that did not have it when it was manufactured

   fluoridation, fluoridisation, fluoridization

   the addition of a fluoride to the water supply (to prevent dental decay)

   type of:

   increase, step-up

   the act of increasing something
3. noun

   a quantity that is added
   “there was an addition to property taxes this year”

   synonyms: gain, increase

   types:

   accretion

   something contributing to growth or increase

   type of:

   indefinite quantity

   an estimated quantity
4. noun

   a component that is added to something to improve it
   “the addition of a bathroom was a major improvement”

   “the addition of cinnamon improved the flavor”

   synonyms: add-on, 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
5. noun

   something combined with what you already have
   “he was a new addition to the staff”

   synonyms: accession

   type of:

   acquisition

   something acquired
6. noun

   a suburban area laid out in streets and lots for a future residential area
   type of:

   suburb, suburban area, suburbia

   a residential district located on the outskirts of a city