factorial

[fak-tawr-ee-uh l, -tohr-] /fækˈtɔr i əl, -ˈtoʊr-/
noun
1.
Mathematics. the product of a given positive integer multiplied by all lesser positive integers: The quantity four factorial (4!) = 4 ⋅ 3 ⋅ 2 ⋅ 1 = 24. Symbol: n!, where n is the given integer.
adjective
2.
Mathematics. of or pertaining to factors or factorials.
3.
of or pertaining to a factor or a factory.
Origin
1810-20; factor + -ial
Related forms
factorially, adverb
British Dictionary definitions for factorials

factorial

/fækˈtɔːrɪəl/
noun
1.
the product of all the positive integers from one up to and including a given integer. Factorial zero is assigned the value of one: factorial four is 1 × 2 × 3 × 4. Symbol: n!, where n is the given integer
adjective
2.
of or involving factorials or factors
Derived Forms
factorially, adverb
Word Origin and History for factorials

factorial

1816 (n.), 1837 (adj.), from factor + -al (2).

factorials in Science
factorial
  (fāk-tôr'ē-əl)   
The product of all of the positive integers from 1 to a given positive integer. It is written as the given integer followed by an exclamation point. For example, the factorial of 4 (written 4!) is 1 × 2 × 3 × 4, or 24.