cofactor

A contributing factor.

(biochemistry) A substance, especially a coenzyme or a metal, that must be present for an enzyme to function.

(biochemistry) A molecule that binds to and regulates the activity of a protein.

(mathematics) The result of a number being divided by one of its factors.

(mathematics, linear algebra, of a matrix) The signed determinant of the submatrix produced by removing the row and column containing a specified element; primarily used in the recursive definition and calculation of the determinant of a matrix.