In linear algebra, reduction refers to applying simple rules to a series of equations or matrices to change them into a simpler form.
In the case of matrices, the process involves manipulating either the rows or the columns of the matrix and so is usually referred to as row-reduction or column-reduction, respectively.
In dynamic analysis, static reduction refers to reducing the number of degrees of freedom.
Static reduction can also be used in finite element analysis to refer to simplification of a linear algebraic problem.
Since a static reduction requires several inversion steps it is an expensive matrix operation and is prone to some error in the solution.