addition

addition — noun

1. the math operation in which several quantities are combined into a single total

1.nounB2
Definition

the math operation in which several quantities are combined into a single total — for example, working out that 3 plus 4 equals 7.

Example

Mr. Chen taught the children simple addition using small wooden blocks.

teach + simple addition (school context)

Nia can do addition in her head, but she still needs paper for division.

do addition (typical verb collocation)

Common collocations
  • simple addition
  • do addition
  • mistake in addition
  • addition and subtraction
Synonyms
  • summation

    more formal or technical; common in maths textbooks

  • totalling

    describes the activity of finding a total rather than the named operation

Antonyms
  • subtraction

    the opposite math operation, taking one number away from another

Usage Note

Uncountable in this sense — never 'an addition' or 'additions' when referring to the math operation. Distinguish from sense 5 (the act of adding something physical) by context: numbers and totals point here.

Common Mistakes

She is good at additions.
She is good at addition.
uncountable when meaning the math operation.

2. used in the fixed phrase 'in addition' or 'in addition to' to bring up another p

2.nounB1
Definition

used in the fixed phrase 'in addition' or 'in addition to' to bring up another person, fact, or thing on top of what you have already mentioned.

Example

In addition to teaching English, Renata runs a small bakery on weekends.

in addition to + -ing

The hotel has a swimming pool, and in addition, every room has a sea view.

'in addition' as sentence connector

Common collocations
  • in addition to
  • in addition,
Synonyms
  • as well as

    more conversational; 'in addition to' is slightly more formal

  • besides

    can replace 'in addition to' but often suggests 'apart from'

  • moreover

    more formal; only replaces 'in addition' as a sentence connector, not 'in addition to'

Grammar Patterns

in addition to + noun/-ing

in addition (sentence connector)

Usage Note

Almost always appears inside the phrase 'in addition' or 'in addition to' — 'in addition' alone joins two sentences, while 'in addition to' takes a noun or -ing form after it. Slightly more formal than 'as well as' or 'and also'.

Common Mistakes

In addition of her salary, she earns extra money.
In addition to her salary, she earns extra money.
the preposition is 'to', not 'of'.
In addition to work hard, he saves money.
In addition to working hard, he saves money.
use the -ing form after 'in addition to'.

3. an extra thing that has been put together with what was already there, often to

3.nounB1
Definition

an extra thing that has been put together with what was already there, often to make it bigger, better, or more complete.

Example

The vintage red scarf was a lovely addition to Nia's winter wardrobe.

a + adjective + addition to + noun

Garlic and lemon are useful additions to this fish recipe.

plural countable use

Common collocations
  • a welcome addition
  • a recent addition
  • the latest addition
  • a useful addition
  • addition to the collection
Synonyms
  • extra

    more informal; emphasises the bonus aspect

  • supplement

    more formal; often suggests something that completes or supports

  • accessory

    narrower; usually a small added item, especially for clothing or equipment

Grammar Patterns

a/the addition to + noun

Usage Note

Almost always followed by 'to + noun' to name what the extra thing is added to. Distinguish from sense 4 (a new person joining a group) by checking whether the referent is a thing or a person.

Common Mistakes

The scarf was a nice addition for her wardrobe.
The scarf was a nice addition to her wardrobe.
the preposition is 'to', not 'for'.

4. a person, baby, or animal who has recently joined a family, team, or other group

4.nounB2
Definition

a person, baby, or animal who has recently joined a family, team, or other group.

Example

Baby Hiro is the newest addition to the Yael family.

the newest addition to the family (set phrase)

Coach Park introduced the team's two new additions before the match started.

plural countable use for new members

Common collocations
  • a new addition
  • the newest addition
  • a welcome addition
  • addition to the family
  • addition to the team
Synonyms
  • newcomer

    neutral; emphasises the person is new but not necessarily welcomed

  • recruit

    narrower; usually for jobs, sports teams, or the military

Grammar Patterns

a/the addition to + group noun

Usage Note

Subject is typically a person, baby, or pet, and the phrase usually ends with 'to + group noun' (the family, the team, the staff). Distinguish from sense 3 by the referent being animate.

Common Mistakes

The baby is a new addition for our family.
The baby is a new addition to our family.
use 'to', not 'for'.

5. the action of putting one substance, ingredient, or feature into something so th

5.nounB2
Definition

the action of putting one substance, ingredient, or feature into something so that it becomes part of it.

Example

The addition of fresh basil completely changed the flavour of the tomato sauce.

the addition of + ingredient

With the addition of a small fan, the kitchen feels much cooler in summer.

with the addition of + noun (causal)

Common collocations
  • the addition of
  • with the addition of
  • ban the addition of
  • after the addition of
Synonyms
  • introduction

    more formal; emphasises bringing something in for the first time

  • inclusion

    stresses being made part of a set rather than mixed in

Antonyms
  • removal

    the opposite act — taking the substance out

Grammar Patterns

the addition of + noun

Usage Note

Almost always uncountable and used in the structure 'the addition of X (to Y)'. Distinguish from sense 3: this names the act, while sense 3 names the thing that has been added.

Common Mistakes

The addition with sugar made it sweeter.
The addition of sugar made it sweeter.
use 'of' before the substance being added.

6. a new room, wing, or section that has been built onto a home, school, or similar

6.nounB2
Definition

a new room, wing, or section that has been built onto a home, school, or similar structure to make it larger.

Example

The Garcias built a sunny addition at the back of their house for their grandmother.

build an addition (American usage)

The school's new addition will hold three science labs and a small library.

new addition (school building context)

Common collocations
  • build an addition
  • a two-storey addition
  • an addition to the house
  • a new addition
Synonyms
  • extension

    preferred in British English for the same idea

  • annex

    usually a separate-looking section, sometimes connected by a corridor

  • wing

    a large side section, more common for big buildings like hospitals or schools

Grammar Patterns

an addition to + building

Usage Note

Common in American English; British speakers often prefer 'extension' for the same idea. Subject is usually a piece of a building (room, wing, storey) rather than furniture or decoration.

Common Mistakes

They built an addition for their house last summer.
They built an addition to their house last summer.
the preposition is 'to', not 'for'.
Idioms

in addition (to somebody/something)

idiom

Used to introduce an extra person or thing that is being included.

In addition to his job, Tom volunteers at a local shelter.

We bought a new sofa. In addition, we got a coffee table.

Word family

Synonym discussion

Sense: noun/3

These words all describe something joined to what is already there, but they differ in tone and scope. 'Addition' is the most general and is used in everyday speech: a new scarf, a new app feature, or a new family pet can all be a 'welcome addition'. 'Supplement' is more formal and often suggests something that completes or strengthens, like a vitamin supplement or a supplement to a contract. 'Extra' is the most informal and emphasises that the item is a bonus you didn't have to have, as in 'a small extra at no charge'. 'Accessory' is narrower and usually refers to a small item paired with clothing, a phone, or a piece of equipment, such as a belt or a camera strap. So you might say a hat is a stylish accessory, a vitamin is a daily supplement, free shipping is an extra, and the new puppy is a noisy but lovable addition to the family.

addition ↗supplement ↗extra ↗accessory ↗

Common collocations

Nouns

Adverbs

Phrases

  • in addition
  • in addition to
  • a welcome addition
  • the latest addition
  • a new addition
  • the addition of

Prepositions

Etymology

LatinOld FrenchMiddle EnglishEnglish

The word came into English in the late 1300s from Old French 'addicion' meaning a joining or increase, which itself came from Latin 'additio', formed on 'addere' — built from 'ad-' (to) plus 'dare' (to give). So at its root, an addition is something 'given to' what is already there. The math sense and the everyday 'extra thing' sense both grew naturally from this idea of giving more.