- extending between the vertices of any two nonadjacent angles in a polygonal figure or between any two vertices not in the same face in a polyhedral figure
- moving or extending obliquely, esp. at a 45° angle; slanting
- having slanting markings, lines, etc.
Origin of diagonalClassical Latin diagonalis from Classical Greek diag?nios from dia-, through + g?nia, an angle, corner: see knee
- a diagonal line or plane
- any diagonal course, row, order, or part
- cloth woven with diagonal lines; twill