diagonal

1 of 2

adjective

di·​ag·​o·​nal dī-ˈa-gə-nᵊl 

-ˈag-nəl

1

a

: joining two vertices of a rectilinear figure that are nonadjacent or two vertices of a polyhedral figure that are not in the same face

b

: passing through two nonadjacent edges of a polyhedron

a diagonal plane

2

a

: inclined obliquely from a reference line (such as the vertical)

wood with a diagonal grain

b

: having diagonal markings or parts

a diagonal weave

diagonal

2 of 2

noun

1

: a diagonal straight line or plane

2

a(1)

: a diagonal direction

(2)

: a diagonal row, arrangement, or pattern

b

: something oriented in diagonal position

3

: slash sense 4

Phrases

on the diagonal

: in an oblique direction : diagonally

Synonyms

Adjective

• oblique
• sloping
• leaning
• sloped

Noun

• slope
• inclination
• incline

Examples of diagonal in a Sentence

Adjective

The blanket is covered with diagonal stripes.

the diagonal design ran up the wall all the way from the lower left to the upper right-hand corner

Noun

a design with strong diagonals

the ramp was set at a low diagonal to make it easier for physically challenged patrons

Recent Examples on the Web

Adjective

The tee shot follows a cape-style layout, with a diagonal pond guarding the fairway from left to right. —Tim Corlett, Forbes.com, 19 June 2025

The diagonal stripe has been used by countless teams around the world and was even adopted by next summer’s joint men’s World Cup hosts, the United States. —Caoimhe O'Neill, New York Times, 10 June 2025

Noun

The video starts with Rice passing to Saka on the right, before stepping forward to arrow a left-footed diagonal to the opposite flank. —Stuart James, The Athletic, 30 Apr. 2024

Late in his career, he was reinvented as a ‘quarterback’, pinging diagonals from deep with machine-like precision. —The Athletic Uk Staff, New York Times, 6 Apr. 2025

Word History

Etymology

Adjective

Latin diagonalis, from Greek diagōnios from angle to angle, from dia- + gōnia angle; akin to Greek gony knee — more at knee entry 1

First Known Use

Adjective

1563, in the meaning defined at sense 1a

Noun

1571, in the meaning defined at sense 1

Phrases Containing diagonal

• diagonal matrix
• on a diagonal
• on the diagonal
• principal diagonal

Rhymes for diagonal

• hexagonal
• octagonal
• tetragonal

Kids Definition

diagonal

1 of 2 adjective

di·​ag·​o·​nal dī-ˈag-ən-ᵊl 

-ˈag-nəl

1

: joining two opposite corners of a four-sided figure

2

: running in a slanting direction

diagonally

-ən-ᵊl-ē

-nə-lē

adverb

diagonal

2 of 2 noun

1

: a diagonal line or direction

2

: a diagonal row, arrangement, or pattern

3

: slash entry 2 sense 2