Joining two not adjacent angles of a quadrilateral or multilateral figure; running across from corner to corner; crossing at an angle with one of the sides.(adjective)
source: webster1913
noun (n)
(geometry) a straight line connecting any two vertices of a polygon that are not adjacent(noun.shape)
source: wordnet30
a line or cut across a fabric that is not at right angles to a side of the fabric(noun.shape)
an oblique line of squares of the same color on a checkerboard(noun.group)
Example: The bishop moves on the diagonals.
source: wordnet30
(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.group)
source: wordnet30
a punctuation mark (/) used to separate related items of information(noun.communication)