triangle

A triangle is a flat shape with three sides and three angles, like a slice of pizza, a yield sign, or the Greek letter delta. If you look carefully, you'll notice triangles all around you!

A triangle is a polygon, which is a closed shape like a square or a hexagon, but a triangle has only three sides. Wedges of pie and some tortilla chips are shaped like triangles. If you invite your crush to a movie and they bring a date, you have yourself a love triangle. Triangle comes from the Latin word triangulus, "three-cornered" or "having three angles," from the roots tri-, "three," and angulus, "angle or corner."

Definitions of triangle
  1. noun
    a three-sided polygon
    synonyms: trigon, trilateral
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    types:
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    acute triangle, acute-angled triangle
    a triangle whose interior angles are all acute
    equiangular triangle, equilateral triangle
    a three-sided regular polygon
    isosceles triangle
    a triangle with two equal sides
    oblique triangle
    a triangle that contains no right angle
    obtuse triangle, obtuse-angled triangle
    a triangle that contains an obtuse interior angle
    right triangle, right-angled triangle
    a triangle with one right angle
    scalene triangle
    a triangle with no two sides of equal length
    cuneus, wedge, wedge shape
    any shape that is triangular in cross section
    delta
    an object shaped like an equilateral triangle
    type of:
    polygon, polygonal shape
    a closed plane figure bounded by straight sides
  2. noun
    something approximating the shape of a triangle
    “the coastline of Chile and Argentina and Brazil forms two legs of a triangle
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    type of:
    form, shape
    the spatial arrangement of something as distinct from its substance
  3. noun
    any of various triangular drafting instruments used to draw straight lines at specified angles
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    type of:
    drafting instrument
    an instrument used by a draftsman in making drawings
  4. noun
    a percussion instrument consisting of a metal bar bent in the shape of an open triangle
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    type of:
    percussion instrument, percussive instrument
    a musical instrument in which the sound is produced by one object striking another
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