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
How to Properly Retire a Flag While retiring a flag involves taking it down, folding it into a triangle, and respectfully burning it, there are specific protocols to follow.
—
Jennifer Prince,
Southern Living,
3 July 2026
The glowing ribbon of the Milky Way tumbles directly through this cosmic triangle before arcing towards the southern horizon, though its diffuse light will be hidden behind a veil of moonlight on the night of the full moon.
—
Anthony Wood,
Space.com,
2 July 2026
On the left, Hudson, an avid reader, sat reading a book while wearing a brown triangle bikini with a thick band and matching swim bottoms.
—
Chanel Vargas,
InStyle,
2 July 2026
The chemistry among the cast is serviceable and gets the job done, and there’s a love triangle that evolves over the course of the season.
—
Olivia Singh,
Forbes.com,
1 July 2026
See All Example Sentences for triangle
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Jennifer Prince,
Southern Living,
3 July 2026
The glowing ribbon of the Milky Way tumbles directly through this cosmic triangle before arcing towards the southern horizon, though its diffuse light will be hidden behind a veil of moonlight on the night of the full moon.
—
Anthony Wood,
Space.com,
2 July 2026
On the left, Hudson, an avid reader, sat reading a book while wearing a brown triangle bikini with a thick band and matching swim bottoms.
—
Chanel Vargas,
InStyle,
2 July 2026
The chemistry among the cast is serviceable and gets the job done, and there’s a love triangle that evolves over the course of the season.
—
Olivia Singh,
Forbes.com,
1 July 2026
See All Example Sentences for triangle
Cite this Entry
“Triangle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/triangle. Accessed 5 Jul. 2026.
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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Merriam-Webster unabridged
