diagonal

American  

[dahy-ag-uh-nl, -ag-nl] / daɪˈæg ə nl, -ˈæg nl /

adjective

1. Mathematics.

   1. connecting two nonadjacent angles or vertices of a polygon or polyhedron, as a straight line.

   2. extending from one edge of a solid figure to an opposite edge, as a plane.

2. having an oblique direction.

3. having oblique lines, ridges, markings, etc.

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noun

diagonals plural

1. a diagonal line or plane.

2. virgule.

3. a diagonal row, part, pattern, etc.

4. Manège. (of a horse at a trot) the foreleg and the hind leg, diagonally opposite, which move forward simultaneously.

5. diagonal cloth.

6. Mathematics. a set of entries in a square matrix running either from upper left to lower right main diagonal, or principal diagonal or lower left to upper right secondary diagonal.

7. Chess. one of the oblique lines of squares on a chessboard.

   He advanced his bishop along the open diagonal.

diagonal British  

/ daɪˈæɡənəl /

adjective

1. maths connecting any two vertices that in a polygon are not adjacent and in a polyhedron are not in the same face

2. slanting; oblique

3. marked with slanting lines or patterns

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noun

1. maths a diagonal line or plane

2. chess any oblique row of squares of the same colour

3. cloth marked or woven with slanting lines or patterns

4. something put, set, or drawn obliquely

5. another name for solidus

6. one front leg and the hind leg on the opposite side of a horse, which are on the ground together when the horse is trotting

diagonal Scientific  

/ dī-ăg′ə-nəl /

1. Connecting two nonadjacent corners in a polygon or two nonadjacent corners in a polyhedron that do not lie in the same face.

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1. A diagonal line segment.

Other Word Forms

Derived Forms

• nondiagonal
  adjective
• diagonally
  adverb
• nondiagonally
  adverb

Inflected Forms

Nouns

• diagonals
  plural

Etymology

Origin of diagonal

First recorded in 1535–45; from Latin diagōnālis, from Greek diagṓn(ios) “from angle to angle” + Latin -ālis adjective suffix; see dia-, -gon, -al ¹

Explanation

A diagonal is made out of a straight line that's set at an angle instead of straight up or across. If you picture a square and draw a line connecting the opposite corners, that’s a diagonal line. You’ll find diagonal lines in geometry, and also in the world around you. A quarterback might throw a diagonal pass that angles across the field, or you might buy a snazzy new leotard with diagonal stripes. Diagonal can be either a noun or an adjective. You could call the steep slope of a hill a diagonal across the sky, or you could talk about the diagonal hillside reaching up toward the clouds.

Example Sentences

After the break, Bellingham's position was a lot more as a number 10 than a supporting midfielder to Anderson, which made making those diagonal runs into the space behind the pressing wing-back more viable.

From BBC • Jun. 28, 2026

Walking in these diagonal directions, as well as 5 feet in the straight compass directions, shows that many pairs of dots on this giant chessboard are exactly 5 feet apart.

From Slate • Jun. 22, 2026

SpotGamma explains that a put diagonal spread combines the sale of a shorter-dated put with the purchase of a longer-dated put at a different strike price.

From MarketWatch • Jun. 1, 2026

The chip is giant, taking up an entire 300 millimeter silicon wafer, almost a foot long across the chip’s diagonal line.

From Barron's • May 11, 2026

“I’m going to mark the ones where we know the Gamemakers’ weapon follows us out past the jungle, so we’ll stay clear of those,” says Peeta, drawing diagonal lines on the fog and wave beaches.

From "Catching Fire" by Suzanne Collins

Related Words

• crosswise
• oblique
• slanted