a square matrix with all elements not on the main diagonal equal to zero

connecting two nonadjacent corners of a plane figure or any two corners of a solid that are not in the same face

(geometry) a straight line connecting any two vertices of a polygon that are not adjacent

an oblique line of squares of the same color on a checkerboard

(mathematics) a set of entries in a square matrix running diagonally either from the upper left to lower right entry or running from the upper right to lower left entry

(mathematics) a rectangular array of quantities or expressions set out by rows and columns; treated as a single element and manipulated according to rules

the body substance in which tissue cells are embedded