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
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
see also:
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
Idaho Statesman,
3 July 2026
Mbappé took a crossover step to get around Viktor Gyökeres and from just outside the 6-yard box sent a diagonal shot inside the far post.
—
CBS News,
1 July 2026
Manon Bischoff,
Scientific American,
19 June 2026
The dog is ahead and has stopped by the tree that bisects the diagonal; the girl with the bright red coat who seems to be paused behind him.
—
Literary Hub,
10 June 2026
See All Example Sentences for diagonal
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Adjective
Knoxville took advantage of that second life seven minutes later when Teddy Baker fired a diagonal cross to Mikkel Gøling in the box.
—
Idaho Statesman,
3 July 2026
Mbappé took a crossover step to get around Viktor Gyökeres and from just outside the 6-yard box sent a diagonal shot inside the far post.
—
CBS News,
1 July 2026
Noun
The most astonishing thing about this is that these numbers appear in the simplest contexts, such as when calculating the circumference of a circle or the diagonal of a square.
—
Manon Bischoff,
Scientific American,
19 June 2026
The dog is ahead and has stopped by the tree that bisects the diagonal; the girl with the bright red coat who seems to be paused behind him.
—
Literary Hub,
10 June 2026
See All Example Sentences for diagonal
Cite this Entry
“Diagonal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diagonal. Accessed 5 Jul. 2026.
Copy CitationKids 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
adverb
-ən-ᵊl-ē,
-nə-lē
diagonal
2 of 2 noun1
: a diagonal line or direction
2
: a diagonal row, arrangement, or pattern
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