diagonal

Short definition from Wiktionary

Adjective

1. 1
   Joining two nonadjacent vertices (of a polygon or polyhedron).
2. 2
   Having slanted or oblique lines or markings.
3. 3
   Having a slanted or oblique direction.
4. 4
   Of or related to the cater-corner (diagonally opposite) legs of a quadruped, whether the front left and back right or front right and back left.

Noun

1. 1
   A line joining non-adjacent vertices of a polygon.
2. 2
   Anything forming or resembling such a line: A line or plane at an oblique angle to another.
3. 3
   Anything forming or resembling such a line: A line or cut across a fabric at an oblique angle to its sides.
4. 4
   Anything forming or resembling such a line: Synonym of slash ⟨/⟩.

Proper noun

1. 1
   A city and town in Iowa.