trianglenoun [ C ]
uk/ˈtraɪ.æŋ.ɡəl/us/ˈtraɪ.æŋ.ɡəl/B2 a flat shape with three straight sides:
an equilateral/isosceles triangle
anything that has three straight sides:
Which earrings did you buy in the end - the triangles or the circles?
a musical instrument consisting of a thin metal bar bent into a triangle shape that is hit with a metal bar to make a sound
US UK set square a flat piece of metal or plastic in the shape of a triangle with one angle of 90°, used for drawing angles
also frame a three-sided frame for arranging the balls at the start of a game of billiards, pool, etc.
More examples
- Draw a perpendicular from the vertex of the triangle to its base.
- A triangle is a shape with three sides.
- The cloth was decorated with triangles of different colours.
- We cut some triangles of cheese.
- To make a star, put two triangles together.
Thesaurus: synonyms and related words
Geometrical shapes
- -cornered
- -dimensional
- arch
- circular
- cuboid
- cylinder
- cylindrical
- dome
- hexagon
- incongruent
- isometric
- lozenge
- octagon
- oval
- ovoid
- parallelogram
- polygon
- quadrilateral
- rhombus
- spherical
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You can also find related words, phrases, and synonyms in the topics:
Musical instruments
Geometrical & mathematical instruments
Snooker, pool & billiards