fac•to•ri•al (fÃ¦kˈtɔr i əl, -ˈtoʊr-)

*n. * ** 1. ** 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.

*adj. * ** 2. ** of or pertaining to factors or factorials.

** 3. ** of or pertaining to a factor or a factory.

[1810–20]

**fac•to′ri•al•ly,** *adv. *