What does addition mean?
Addition is a noun with two closely related meanings: the act of joining something to something else, and the thing that has been joined. It also carries a precise mathematical sense, denoting the operation of combining numbers to find their sum — the most basic of the four arithmetic operations. Beyond mathematics, addition appears constantly in everyday speech and writing, whether describing a new wing on a museum, a recent hire at a company, or a newborn welcomed into a family. The phrase "in addition to" serves as a standard formal way of saying "as well as" or "besides," making the word indispensable in essays, reports, and professional communication. Neutral in tone and universal across English-speaking regions, addition is a versatile word that bridges everyday language and technical usage. Its Latin roots connect it to a wider family of words including additional, additive, and add, all sharing the core idea of putting things together.
The act or process of adding something to something else; a thing or person that has been added.
"The sculpture garden is a striking addition to the city's waterfront."
When referring to buildings, American English favors "addition" while British English often uses "extension."
(Mathematics) The process of calculating the total or sum of two or more numbers or quantities.
"Children learn simple addition before moving on to multiplication."
This sense is typically used in educational and technical contexts.
The plural "additions" refers to multiple things that have been added, such as several new features, rooms, or members.
"Recent additions to the menu include two vegetarian dishes."
Every time you say 'in addition,' you're echoing the Latin 'additio' — the same root that gave us the plus sign's job description.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of addition
Addition comes from the Latin "additio," meaning "an adding to," derived from the verb "addere" (to add), which itself combines "ad-" (to) with "dere" (to put or place). The word entered English via Old French in the late Middle Ages, initially carrying both its general sense of adding something and its mathematical sense. It shares its Latin root with related words such as "additional," "additive," and "addend," as well as more distant relatives like "date" and "dative," which trace back to the same Latin verb of giving or placing.
Related word forms
How addition is actually used
"Addition" is neutral in register and works in both formal and informal contexts. The phrase "in addition to" is a common formal connector meaning "besides" or "as well as." When referring to a building extension, British English often uses "extension," while American English more commonly uses "addition."
Easily confused with addition
An edition is a particular version or printing of a published work, while an addition is something added to something else.
Admission means the act of allowing entry or acknowledging a fact, whereas addition means the act of adding something.