Illustration of triangle
- 1 equilateral
- 2 acute
- 3 obtuse
- 4 scalene
- 5 isosceles
- 6 right triangle
triangle
noun
tri·an·gle
ˈtrī-ˌaŋ-gəl 
1
: a polygon having three sides compare spherical triangle
2
a
: a percussion instrument consisting of a rod of steel bent into the form of a triangle open at one angle and sounded by striking with a small metal rod
b
: a drafting instrument consisting of a thin flat right-angled triangle of wood or plastic with acute angles of 45 degrees or of 30 degrees and 60 degrees
3
: a situation in which one member of a couple is involved in a love affair with a third person
Examples of triangle in a Sentence
She cut the sandwiches into triangles.
Recent Examples on the Web
The three of them had this magic triangle.
—
Shirley Halperin, Rolling Stone, 13 Nov. 2025
Materialists, a romantic comedy-drama written and directed by Celine Song, follows a love triangle among characters played by Dakota Johnson, Chris Evans and Pedro Pascal.
—Paul Grein, Billboard, 13 Nov. 2025
Geometric forms are at the heart of the collection, with the use of the triangle representing balance, proportion and strength.
—Sofia Celeste, Footwear News, 13 Nov. 2025
Refashion uses modules—often simple shapes, like rectangles and triangles—to help users lay out garment patterns, allowing designers to create digital pieces that can be reimagined into multiple garments.
—Meghan Hall, Sourcing Journal, 11 Nov. 2025
See All Example Sentences for triangle
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Shirley Halperin, Rolling Stone, 13 Nov. 2025
Materialists, a romantic comedy-drama written and directed by Celine Song, follows a love triangle among characters played by Dakota Johnson, Chris Evans and Pedro Pascal.
—Paul Grein, Billboard, 13 Nov. 2025
Geometric forms are at the heart of the collection, with the use of the triangle representing balance, proportion and strength.
—Sofia Celeste, Footwear News, 13 Nov. 2025
Refashion uses modules—often simple shapes, like rectangles and triangles—to help users lay out garment patterns, allowing designers to create digital pieces that can be reimagined into multiple garments.
—Meghan Hall, Sourcing Journal, 11 Nov. 2025
See All Example Sentences for triangle
Cite this Entry
“Triangle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/triangle. Accessed 14 Nov. 2025.
Copy CitationKids Definition
triangle
noun
tri·an·gle
ˈtrī-ˌaŋ-gəl
1
: a figure that has three sides and three angles : a polygon that has three sides
2
: a percussion instrument made of a steel rod bent into a triangle open at one corner which is played by striking with a metal rod
3
: a drafting instrument consisting of a thin flat right-angled triangle
Medical Definition
triangle
noun
tri·an·gle
ˈtrī-ˌaŋ-gəl
: a three-sided region or space and especially an anatomical one see anterior triangle, carotid triangle, femoral triangle, posterior triangle, suboccipital triangle
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