• noun:   (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
• noun:   an oblique line of squares of the same color on a checkerboard

  Example: "The bishop moves on the diagonals"

• noun:   a line or cut across a fabric that is not at right angles to a side of the fabric
• noun:   (geometry) a straight line connecting any two vertices of a polygon that are not adjacent
• noun:   a punctuation mark (/) used to separate related items of information
• adjective:   at an angle; especially connecting two nonadjacent corners of a plane figure or any two corners of a solid that are not in the same face

  Example: "A diagonal line across the page"

• adjective:   having an oblique or slanted direction

Related words...