Diagonal means a straight line from one corner across to the opposite corner of a four-sided figure.

Diagonal is derived from the Greek diagnios from the Latin diagnlis which means from angle to angle.

Its use is most commonly found in Mathematics where, in planar (two dimensional) geometry, it means to join two non-adjacent vertices (point where the sides of an angle intersect) or of a polygon. In three dimensional geometry; it means joining two corners of a polyhedron on different faces.

Simply put, it is a sloping line that joins two non-adjacent corners in a shape. It is something that is arranged obliquely.

A diagonal brace is frequently used in engineering as a cross brace to add strength and rigidity to a rectangular structure or in a rhombus.

In fashion and design diagonal can be used to indicate a pattern that follows a diagonal arrangement as in 'a green scarf with a yellow diagonal stripe'.

Its use is most commonly found in Mathematics where, in planar (two dimensional) geometry, it means to join two non-adjacent vertices (point where the sides of an angle intersect) or of a polygon. In three dimensional geometry; it means joining two corners of a polyhedron on different faces.

Simply put, it is a sloping line that joins two non-adjacent corners in a shape. It is something that is arranged obliquely.

A diagonal brace is frequently used in engineering as a cross brace to add strength and rigidity to a rectangular structure or in a rhombus.

In fashion and design diagonal can be used to indicate a pattern that follows a diagonal arrangement as in 'a green scarf with a yellow diagonal stripe'.