# triangle

/ˈtɹaɪˌæŋɡəɫ/ (US) · /tɹˈaɪæŋɡəl/ (UK)

Source: https://englishreference.com/word/triangle
Updated: 2026-08-15

## Senses

### 1. the shape

noun · CEFR A1

a flat shape that has three straight sides and three corners.

For teachers: a polygon with three sides and three interior angles.

- The children learned how to draw a square, a circle, and a triangle.
- The architect used a series of interlocking triangles to distribute the weight of the roof across the glass walls.

### 2. musical instrument

noun · CEFR B1

a musical instrument made of a metal bar bent into a triangle shape that you hit with a small metal stick.

For teachers: an idiophone percussion instrument consisting of a steel rod bent into a triangular shape, typically struck with a metal beater.

- The boy waited for his turn to hit the triangle during the school concert.
- The composer added a single triangle stroke at the end of the movement to provide a bright, shimmering finish to the orchestral texture.

### 3. love triangle

noun · CEFR B2

a complicated situation where three people are involved in a romantic relationship with each other.

For teachers: a romantic relationship involving three people, often characterized by conflict or jealousy.

- The movie is about a messy love triangle between two best friends and a new neighbor.
- The novel explores the psychological tension within a love triangle, focusing on how secrets eventually erode the trust between the three protagonists.

### 4. drawing tool

noun · CEFR B2

a flat, plastic tool shaped like a triangle used for drawing straight lines and angles.

For teachers: a technical drawing instrument, often called a set square, used to provide a straightedge at a specific angle to a baseline.

- You will need a ruler and a triangle to finish your geometry homework.
- The engineering student used a plastic triangle to ensure that every vertical line in the blueprint was perfectly perpendicular to the base.

### 5. billiards/pool tool

noun · CEFR B1

a frame used to arrange the balls into a triangle before starting a game of pool.

For teachers: a triangular frame used to rack the balls at the beginning of a game of billiards, pool, or snooker.

- He placed the balls inside the triangle and made sure they were tight before the first shot.
- After the previous frame ended, the referee carefully positioned the triangle to reset the balls for the next round of the tournament.

## Examples

- The children learned how to draw a triangle in school.
- The percussionist waited for the conductor's signal before striking the triangle during the final movement.
- In Euclidean geometry, the sum of the interior angles of a triangle always equals one hundred and eighty degrees, a fundamental principle used in various engineering calculations.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.