plural additions
1
: the act or process of joining something to something else : the act or process of adding something
—often + of
The soup was thickened by the addition of cream in the last stage of cooking.
The town welcomed the addition of three new computers to the library.
2
mathematics
: the act or process of adding numbers
The children learned addition and subtraction.
3
: something or someone more that is included : something or someone that is added
The museum's collection includes several new additions.
—usually + toan addition to the family [=a new member of the family, such as a newborn baby]
The sculpture is the newest addition to the museum's collection.
4
US
: a part of a building that is built after the original part has been completed
The addition expands the kitchen and adds a second bathroom.
Cite this Entry
“Addition.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/addition. Accessed 23 Jun. 2026.
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