[ dʌɪ'ag(ə)n(ə)l ]
■ adjective denoting a straight line joining opposite corners of a rectangle, square, or other figure.
↘(of a line) straight and at an angle; slanting.
↘ Mathematics denoting a matrix with non-zero elements only on the ~ running from the upper left to the lower right.
■ noun a ~ line.
Derivatives
~ly adverb
Origin
C16: from L. ~is , from Gk diagōnios 'from angle to angle', from dia 'through' + gōnia 'angle'.