Did you know?

Click any word in a definition or example to find the entry for that word

triangle - definition and synonyms


What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.



Thesaurus diagram

The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning.

noun [countable]     triangle pronunciation in British English
Word Forms
  1. 1
    maths a flat shape that has three straight sides and three angles
    1. a.
      something that has the shape of a triangle

      a triangle of land

  2. 2
    Sound effect a simple musical instrument consisting of a metal triangle that you hit with a metal bar. The triangle is a percussion instrument.
  3. 3
    a situation in which three people or groups are involved, although they have different opinions, ideas, or aims

    a love triangle

quiz invitation


a description of an economic or political situation based on analysis of information at the present time

BuzzWord Article

Open Dictionary


an unregulated form of capitalism that features financial deregulation, privatisation and low tax for high earners

add a word


A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog
Macmillan learn live love play