# diagonal

/daɪˈæɡənəɫ/ (US) · /daɪˈæɡənəl/ (UK)

Source: https://englishreference.com/word/diagonal
Updated: 2026-08-08

## Senses

### 1. slanted or at an angle

adjective · CEFR B2

describing a straight line that is slanted, rather than going straight across or straight up and down.

For teachers: having a slanted or oblique direction; neither horizontal nor vertical.

- The shirt has a pattern of diagonal stripes in blue and white.
- The architect incorporated several diagonal support beams to give the glass atrium a more dynamic and modern aesthetic.

### 2. joining opposite corners

adjective · CEFR B2

connecting two opposite corners of a square, rectangle, or other flat shape.

For teachers: joining two non-adjacent vertices of a polygon, such as the opposite corners of a quadrilateral.

- Draw a diagonal line from the top-left corner to the bottom-right corner.
- To calculate the length of the diagonal, you must apply the Pythagorean theorem to the sides of the rectangle.

### 3. a slanted line

noun · CEFR B2

a straight line that joins opposite corners or goes across at an angle.

For teachers: a straight line joining non-adjacent vertices of a polygon or any slanted line or direction.

- The hikers took a shortcut across the field, walking on a diagonal toward the gate.
- The composition of the painting is dominated by a strong diagonal that leads the viewer's eye from the foreground into the distance.

## Examples

- The shirt has a pattern of thin diagonal stripes.
- To save time, the hikers took a diagonal path across the field instead of following the perimeter fence.
- The architect used diagonal bracing to reinforce the structure against lateral wind forces while maintaining the building's aesthetic profile.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.