1
: one who acts or transacts business for another: such as
a
b
: one that lends money to producers and dealers (as on the security of accounts receivable)
2
a(1)
: one that actively contributes to the production of a result : ingredient
price wasn't a factor in the decision
(2)
: a substance that functions in or promotes the function of a particular physiological process or bodily system
a clotting factor that facilitates blood coagulation
b
: a good or service (such as land, labor, or capital) used in the process of production
3
: gene
4
a
: any of the numbers or symbols in mathematics that when multiplied together form a product (see product sense 1)
also
: a number or symbol that divides another number or symbol
b
: a quantity by which a given quantity is multiplied or divided in order to indicate a difference in measurement
costs increased by a factor of 10
factored; factoring
ˈfak-t(ə-)riŋ 
: to work as a factor
1
: to resolve into factors
2
a
: to include or admit as a factor
—used with in or into
factor inflation into our calculations
b
: to exclude as a factor
—used with out
Did you know?
In Latin factor means simply "doer". So in English a factor is an "actor" or element or ingredient in some situation or quantity. Charm can be a factor in someone's success, and lack of exercise can be a factor in producing a poor physique. In math we use factor to mean a number that can be multiplied or divided to produce a given number (for example, 5 and 8 are factors of 40). And in biology a gene may be called a factor, since genes are ingredients in the total organism.
Examples of factor in a Sentence
Noun
There were several factors contributing to their recent decline.
Poor planning was a major factor in the company's failure.
6, 4, 3, and 2 are factors of 12.
Verb
you should factor in inflation in making investment decisions
Recent Examples on the Web
Kim Toscano, Southern Living, 9 July 2025
Of course compensation matters to teachers, but other factors matter too, and reforms can be embraced that don’t require more from taxpayers.
—Carrie Lukas, Forbes.com, 9 July 2025
Michael Loria, USA Today, 8 July 2025
Neither of them were impact players for Minnesota last season, but should factor into Boston’s rotation this year.
—Andrew Callahan, Boston Herald, 8 July 2025
See All Example Sentences for factor
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Noun
Wilt caused by environmental factors is the easiest to manage.
—Kim Toscano, Southern Living, 9 July 2025
Of course compensation matters to teachers, but other factors matter too, and reforms can be embraced that don’t require more from taxpayers.
—Carrie Lukas, Forbes.com, 9 July 2025
Verb
New York’s camp safety council factored natural disasters into their safety considerations as recently as October 2024.
—Michael Loria, USA Today, 8 July 2025
Neither of them were impact players for Minnesota last season, but should factor into Boston’s rotation this year.
—Andrew Callahan, Boston Herald, 8 July 2025
See All Example Sentences for factor
Cite this Entry
“Factor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/factor. Accessed 14 Jul. 2025.
Copy CitationKids Definition
factor
1 of 2 noun
fac·tor
ˈfak-tər
1
: one that buys or sells property for another : agent
2
: something that contributes to the production of a result
price wasn't a factor in our decision
3
: gene
4
: any of the numbers or symbols in mathematics that when multiplied together form a product
especially
: a number that divides another number without leaving a remainder
the factors of 6 are 1, 2, 3, and 6
factor
2 of 2 verb
factored; factoring
-t(ə-)riŋ
1
: to find the mathematical factors of and especially the prime mathematical factors
2
: to act as a factor
attendance will factor into your grade
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