1. [ adjective ] (geometry) 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

"a diagonal line across the page"

Related terms: oblique
2. [ noun ] (mathematics,geometry) a line or cut across a fabric that is not at right angles to a side
Synonyms: bias
Related terms: straight_line
3. [ adjective ] having an oblique or slanted direction
Synonyms: slanting sloping slanted sloped aslope aslant
Related terms: inclined
4. [ noun ] an oblique line of squares of the same color on a checkerboard

"the bishop moves on the diagonals"

Related terms: line line main_diagonal secondary_diagonal chessboard
5. [ 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
Related terms: set square_matrix mathematics diagonalize
6. [ noun ] (geometry) a straight line connecting any two vertices of a polygon that are not adjacent
Related terms: straight_line geometry
7. [ noun ] a punctuation mark (/) used to separate related items of information
Synonyms: slash virgule stroke separatrix solidus
Related terms: punctuation
Similar spelling:   diagonally