noun Mathematics.

- a function defined on a given set, having value 1 for every element of the set and value 0 for every element not contained in the set.
- characteristic polynomial.

noun

- maths a function that assigns the value 1 to the members of a given set and the value 0 to its nonmembers
- statistics a function derived from the probability distribution function that enables the distribution of the sum of given random variables to be analysed