| Noun | 1. | diagonal - (geometry) a straight line connecting any two vertices of a polygon that are not adjacentgeometry - the pure mathematics of points and lines and curves and surfaces straight line - a line traced by a point traveling in a constant direction; a line of zero curvature; "the shortest distance between two points is a straight line" | |
| 2. | diagonal - a line or cut across a fabric that is not at right angles to a side of the fabricstraight line - a line traced by a point traveling in a constant direction; a line of zero curvature; "the shortest distance between two points is a straight line" | |
| 3. | diagonal - an oblique line of squares of the same color on a checkerboard; "the bishop moves on the diagonals"checkerboard - a board having 64 squares of two alternating colors secondary diagonal - the diagonal of a square matrix running from the lower left entry to the upper right entry line - a formation of people or things one behind another; "the line stretched clear around the corner"; "you must wait in a long line at the checkout counter" line - a formation of people or things one beside another; "the line of soldiers advanced with their bayonets fixed"; "they were arrayed in line of battle"; "the cast stood in line for the curtain call" | |
| 4. | diagonal - (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 entrymath, mathematics, maths - a science (or group of related sciences) dealing with the logic of quantity and shape and arrangement set - (mathematics) an abstract collection of numbers or symbols; "the set of prime numbers is infinite" square matrix - a matrix with the same number of rows and columns | |
| 5. | diagonal - a punctuation mark (/) used to separate related items of informationpunctuation mark, punctuation - the marks used to clarify meaning by indicating separation of words into sentences and clauses and phrases | |
| Adj. | 1. | diagonal - 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"oblique - slanting or inclined in direction or course or position--neither parallel nor perpendicular nor right-angular; "the oblique rays of the winter sun"; "acute and obtuse angles are oblique angles"; "the axis of an oblique cone is not perpendicular to its base" | |
| 2. | diagonal - having an oblique or slanted directioninclined - at an angle to the horizontal or vertical position; "an inclined plane" | |