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.

Primary Meanings of addition

the arithmetic operation of summing; calculating the sum of two or more numbers
a suburban area laid out in streets and lots for a future residential area
Full Definitions of addition

n the arithmetic operation of summing; calculating the sum of two or more numbers

plus, summation
Type of:
arithmetic operation
a mathematical operation involving numbers

n 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”
deduction, subtraction
the act of subtracting (removing a part from the whole)
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

n a quantity that is added

“there was an addition to property taxes this year”
gain, increase
something contributing to growth or increase
Type of:
indefinite quantity
an estimated quantity

n 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”
add-on, improver
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something added to enhance food or gasoline or paint or medicine
an addition that was not included in the original plan
annex, annexe, extension, wing
an addition that extends a main building
a supplementary part or accessory
elongation, extension
an addition to the length of something
an additive that enhances the effectiveness of medical treatment
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

n something combined with what you already have

“he was a new addition to the staff”
Type of:
something acquired

n 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

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