Did you know?

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

illusion - 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]     illusion pronunciation in British English
Word Forms
  1. 1
    a false or wrong belief or idea
    illusion that:

    Many people still have the illusion that full employment is possible.

    create/give/maintain the illusion:

    This description creates the illusion that we can solve all our environmental problems.

    be under no illusion/illusions (=not have a false idea):

    We are under no illusion that this money will be enough.

    have no illusions (=realize that something is difficult or unpleasant):

    I had no illusions about the task that lay ahead.

  2. 2
    an appearance or effect that is different from the way that things really are

    For some time, Yeltsin’s rule provided an illusion of stability.

    give/create the illusion of something:

    Glass bricks in the bathroom gave the illusion of lightness and space.



to manipulate someone psychologically so that they begin to question their own perceptions and memories

BuzzWord Article

Open Dictionary

Dunning-Kruger effect

the phenomenon by which an incompetent person is too incompetent to understand his own incompetence

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