Did you know?

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

metastable - 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.

  1. From our crowdsourced Open Dictionary
    in physics and chemistry, relating to a state of a chemical or physical system that is unstable but relatively long-lived provided it is not subjected to major disturbances

    Intriguingly, the measured values of the Higgs boson mass and top quark mass put the universe very close to the boundary between metastable and completely stable.

    Submitted by filz from Italy on 09/11/2014


a lifestyle focussing on simple pleasures such as comfort and cosiness in the home, and spending time with friends and family

BuzzWord Article

Open Dictionary


a form of location that involves the underwater detonation of a bomb which causes sound waves that are picked up by ships

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