- Of or pertaining to a factor.
- (mathematics) Of or pertaining to a factor or factorial.
- (dated) Of or pertaining to a factory.
- (mathematics, combinatorics) The result of multiplying a given number of consecutive integers from 1 to the given number. In equations, it is symbolized by an exclamation mark (!). For example, 5! = 1 * 2 * 3 * 4 * 5 = 120.