(graph theory) A matrix used to determine whether all of the edges of a graph can be traversed without visiting a vertex more than once.

(linear algebra) Any n×n square matrix for which there exists a corresponding inverse matrix (i.e., a second (or possibly the same) matrix such that when the two are multiplied by each other, in either order, the result is the n×n identity matrix).

(computing, also attributively) A two-dimensional array or pattern of dots used (for example, by a display device or a printer) to represent alphanumeric characters and pictures.

(physics) The original formulation of quantum mechanics in which the operators were represented by time-dependent matrices.

(graph theory) A matrix showing the relationship between two classes of objects.

(mathematics) A process by which a matrix (a rectangular table of numbers or abstract quantities that can be added and multiplied) is broken down into simpler numerical building blocks.

(mathematics) A matrix having the same number of rows as columns.

(linear algebra) An identity matrix

(linear algebra, probability theory, statistics) A matrix having the property that the entries in each column are non-negative, real and sum to 1.

(linear algebra) Of a matrix A, another matrix B such that A multiplied by B and B multiplied by A both equal the identity matrix.