addition
Americannoun
-
additions
plural
-
the act or process of adding or uniting.
-
the process of uniting two or more numbers into one sum, represented by the symbol +.
-
the result of adding.
- Synonyms:
- accession, increment, enlargement, increase
-
something added.
- Synonyms:
- appendix, supplement, accession, increment, enlargement, increase
-
a wing, room, etc., added to a building, or abutting land added to real estate already owned.
-
Chemistry. a reaction in which two or more substances combine to form another compound.
idioms
noun
-
the act, process, or result of adding
-
a person or thing that is added or acquired
-
a mathematical operation in which the sum of two numbers or quantities is calculated. Usually indicated by the symbol +
-
a part added to a building or piece of land; annexe
-
obsolete a title following a person's name
-
(adverb) also; as well; besides
-
(preposition) besides; as well as
Usage
What is a basic definition of addition? Addition is a mathematical operation in which two or more numbers are combined to equal a greater number. The word addition also refers to the act of adding. More generally, it refers to an increase or boost applied to something. Addition has a few other senses as a noun. Addition is one of math’s basic operations. Two or more numbers are united to result in a greater number, called a sum. The symbol used for addition is +, which is called a plus sign.Real-life examples: Here are some basic examples of addition: 2 + 2 = 4, 17 + 35 = 52, 143 + 64 = 207. Used in a sentence: I’m teaching the kids to use addition to figure out how much money they need to pay for lunch. An addition is something that has been joined or combined with something else to enhance it or provide more to it. Real-life examples: Recipes can be improved or made more flavorful by using additions such as spices. Accessories and decorations are used as additions to things like cars or clothing to make them look nicer or more stylish. Used in a sentence: Paintings and flowers make nice additions to any room. Relatedly, addition can refer to new rooms or wings that are attached to a building. Used in a sentence: The college is planning a new addition to the campus library. Addition is also used to refer to the act or an instance of adding to something or increasing it in some way. Used in a sentence: The roller coaster became much more popular after the addition of exciting music and amazing decorations.
Synonym Usage
Addition, accessory, adjunct, attachment mean something joined onto or used with something else. Addition is the general word, carrying no implication of size, importance, or kind, but merely that of being joined to something previously existing: an addition to an income, to a building, to one's cares. An accessory is a subordinate addition to a more important thing, for the purpose of aiding, completing, ornamenting, etc.: accessories to a costume. An adjunct is a subordinate addition that aids or assists a main thing or person but is often separate: a second machine as an adjunct to the first. An attachment is an accessory part that may be easily connected and removed: a sewing machine attachment for pleating.
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of addition
First recorded in 1350–1400; Middle English addicio(u)n, from Latin additiōn-, stem of additiō, from addit(us) “added” (past participle of addere “to add”; see add) + -iō -ion
Explanation
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.
Vocabulary lists containing addition
Arithmetic
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
List 1
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
The Number System
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
In addition to tracking Alice Huang, U.S. intelligence officials collected information on Chinese businesses and their leaders and through that process learned about their connections to Jensen Huang, people familiar with the matter said.
From The Wall Street Journal ● Nov. 14, 2026
In addition, MI5 must change the way it prepares and gives evidence, after the High Court case.
From BBC ● Nov. 13, 2026
In addition to the 12 core films, the franchise includes books, video games and television shows.
From Los Angeles Times ● Nov. 13, 2026
As his executor, I spent two years settling his estate, in addition to the two years before his passing working with him and his lawyers on estate planning.
From MarketWatch ● Nov. 13, 2026
Something kept crawling over her body, flickering its antennae as it puzzled over the addition to its home.
From "A Girl Named Disaster" by Nancy Farmer
The brand has undergone a turnaround effort in recent years, and has completed remodels and menu additions since Williams joined in 2024.
From Los Angeles Times ● Nov. 7, 2026
These additions allowed them to simulate how magnetized stars change over time, beginning with the main-sequence stage, when stars generate energy by fusing hydrogen into helium.
From Science Daily ● Nov. 6, 2026
Cloudflare brought in 308 large customers during the quarter and nearly 1,000 over the past year, setting fresh company records for customer additions on both a quarterly and annual basis.
From MarketWatch ● Nov. 5, 2026
"On the supply side, however, we expect difficulties in expanding... output in a short period of time through new capacity additions," he said.
From Barron's ● Oct. 29, 2026
They are new additions to secure knowledge; they are, in our terms, theories.
From "The Invention of Science" by David Wootton
Random Word
Spin the wheel and learn a new word!
Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
